Project Gutenberg's The Boy Mechanic: Volume 1, by Popular Mechanics

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Title: The Boy Mechanic: Volume 1
       700 Things For Boys To Do

Author: Popular Mechanics

Release Date: June 18, 2004 [EBook #12655]

Language: English

Character set encoding: ISO-8859-1

*** START OF THIS PROJECT GUTENBERG EBOOK THE BOY MECHANIC: VOLUME 1 ***




Produced by Don Kostuch




The Boy Mechanic
Vol. 1
700 Things for Boys to Do
800 Illustrations Showing How



Jack Mansfield
+
Ed

Jan 28, 1938

August 1916

From Mother



THE BOY MECHANIC VOLUME I

Transcriber's Notes

This text accurately reproduces the original book except for
adherence to Project Gutenburg guidelines. Each project title is
followed by its original page number to allow use of the
alphabetical contents (index) at the end of the book. The book
used very complex typesetting to conserve space. This
transcription uses simple one-column linear layout.

The text only version is of limited use because of the widespread
occurrence of  diagrams and illustrations. Use the pdf version for
the complete text.

Many projects are of contemporary interest--magic, kites and
boomerangs for example. Try a "Querl" for starters.

There are many projects of purely historical interest, such as
chemical photography, phonographs, and devices for coal
furnaces.

Another class of projects illustrate the caviler attitude toward
environment and health in 1913. These projects involve items
such as gunpowder, acetylene, hydrogen, lead, mercury, sulfuric
acid, nitric acid, cadmium, potassium sulfate, potassium cyanide,
potassium ferrocyanide, copper sulfate, and hydrochloric acid.
Several involve the construction of hazardous electrical devices.
Please view these as snapshots of culture and attitude, not as
suggestions for contemporary activity.

Be careful and have fun or simply read and enjoy a trip into
yesterday.


[Illustration: How to Make a Glider (See page 171)]


THE BOY MECHANIC

VOLUME I

700 THINGS FOR BOYS TO DO

HOW TO CONSTRUCT

WIRELESS OUTFITS, BOATS, CAMP EQUIPMENT,
AERIAL GLIDERS, KITES, SELF-PROPELLED VEHICLES
ENGINES, MOTORS, ELECTRICAL APPARATUS, CAMERAS
AND
HUNDREDS OF OTHER THINGS WHICH DELIGHT EVERY BOY

WITH 800 ILLUSTRATIONS

COPYRIGHTED, 1913, BY H. H. WINDSOR CHICAGO
POPULAR MECHANICS CO.
PUBLISHERS



** A Model Steam Engine [1]

The accompanying sketch illustrates a two-cylinder single-acting,
poppet valve steam engine of home construction.

The entire engine, excepting the flywheel, shaft, valve cams,
pistons and bracing rods connecting the upper and lower plates of
the frame proper, is of brass, the other parts named being of cast
iron and bar steel.

The cylinders, G, are of seamless brass tubing, 1-1/2 in. outside
diameter; the pistons, H, are ordinary 1-1/2 in. pipe caps turned
to a plug fit, and ground into the cylinders with oil and emery.
This operation also finishes the inside of the cylinders.

The upright rods binding the top and bottom plates are of steel
rod about 1/8-in. in diameter, threaded into the top plate and
passing through holes in the bottom plate with hexagonal brass
nuts beneath.

The valves, C, and their seats, B, bored with a countersink bit,
are plainly shown. The valves were made by threading a copper
washer, 3/8 in. in diameter, and screwing it on the end of the
valve rod, then wiping on roughly a tapered mass of solder and
grinding it into the seats B with emery and oil.

The valve rods operate in guides, D, made of 1/4-in. brass tubing,
which passes through the top plate and into the heavy brass bar
containing the valve seats and steam passages at the top, into
which they are plug-fitted and soldered.

The location and arrangement of the valve seats and steam passages
are shown in the sketch, the flat bar containing them being
soldered to the top plate.

The steam chest, A, over the valve mechanism is constructed of

[Illustration: Engine Details]

1-in. square brass tubing, one side being sawed out and the open
ends fitted with pieces of 1/16 in. sheet brass and soldered. in.
The steam inlet is a gasoline pipe connection such as used on
automobiles.

The valve-operating cams, F, are made of the metal ends of an old
typewriter platen, one being finished to shape and then firmly
fastened face to face to the other, and used as a pattern in
filing the other to shape. Attachment to the shaft, N, is by means
of setscrews which pass through the sleeves.

The main bearings, M, on the supports, O, and the crank-end
bearings of the connecting rods, K, are split and held in position
by machine screws with provision for taking them up when worn.

The exhausting of spent steam is accomplished by means of slots,
I, sawed into the fronts of the cylinders at about 1/8 in. above
the lowest position of the piston's top at the end of the stroke,
at which position of the piston the valve rod drops into the
cutout portion of the cam and allows the valve to seat.

All the work on this engine, save turning the pistons, which was
done in a machine shop for a small sum, and making the flywheel,
this being taken from an old dismantled model, was accomplished
with a hacksaw, bench drill, carborundum wheel, files, taps and
dies. The base, Q, is made of a heavy piece of brass.

The action is smooth and the speed high. Steam is supplied by a
sheet brass boiler of about 3 pt. capacity, heated with a Bunsen
burner.
--Contributed by Harry F. Lowe, Washington, D. C.



** Magic Spirit Hand [2]

The magic hand made of wax is given to the audience for
examination, also a board which is suspended by four pieces of
common picture-frame wire. The hand is placed upon the board and
answers, by rapping, any question asked by members of the
audience. The hand and the board may be examined at any time and
yet the rapping can be continued, though surrounded by the
audience.

The Magic Wand, London, gives the secret of this spirit hand as
follows: The hand is prepared by concealing in the wrist a few
soft iron plates, the wrist being afterwards bound with black
velvet as shown in Fig. 1. The board is hollow, the top being made
of thin veneer (Fig. 2). A small magnet, A, is connected to a
small flat pocket lamp battery, B. The board is suspended by four
lengths of picture-frame wire one of which, E, is

[Illustration: Wax Hand on Board and Electrical Connections]

connected to the battery and another, D, to the magnet. The other
wires, F and G, are only holding wires. All the wires are fastened
to a small ornamental switch, H, which is fitted with a connecting
plug at the top. The plug can be taken out or put in as desired.

The top of the board must be made to open or slide off so that
when the battery is exhausted a new one can be installed.
Everything must be firmly fixed to the board and the hollow space
filled in with wax, which will make the board sound solid when
tapped.

In presenting the trick, the performer gives the hand and board
with wires and switch for examination, keeping the plug concealed
in his right hand. When receiving the board back, the plug is
secretly pushed into the switch, which is held in the right hand.
The hand is then placed on the board over the magnet. When the
performer wishes the hand to move he pushes the plug in, which
turns on the current and causes the magnet to attract the iron in
the wrist, and will, therefore, make the hand rap. The switch can
be made similar to an ordinary push button so the rapping may be
easily controlled without detection by the audience.




** Making Skis and Toboggans [3]

During the winter months everyone is thinking of skating, coasting
or ski running and jumping. Those too timid to run down a hill
standing upright on skis must take their pleasure in coasting or
skating.

The ordinary ski can be made into a coasting ski-toboggan by
joining two pairs together with bars without injury to their use
for running and jumping. The ordinary factory-made skis cost from
$2.50 per pair up, but any boy can make an excellent pair far 50
cents.

In making a pair of skis, select two strips of Norway pine free
from knots, 1 in. thick, 4 in. wide and 7 or 8 ft. long. Try to
procure as fine and straight a grain as possible. The pieces are
dressed thin at both ends leaving about 1 ft. in the center the
full thickness of 1 in., and gradually thinning to a scant 1/2 in.
at the ends. One end of each piece is tapered to a point beginning
12 in. from the end. A groove is cut on the under side, about 1/4
in. wide and 1/8 in. deep, and running almost the full length of
the ski. This will make it track straight and tends to prevent
side slipping. The shape of each piece for a ski, as it appears
before bending, is shown in Fig. 1.

The pointed end of each piece is placed in boiling water for at
least 1 hour, after which the pieces are ready for bending. The
bend is made on an ordinary stepladder. The pointed ends are stuck
under the back of one step and the other end securely tied to the
ladder, as shown in Fig. 2. They should remain tied to the ladder
48 hours in a moderate temperature, after which they will hold
their shape permanently.

The two straps, Fig. 3, are nailed an a little forward of the
center of gravity so that when the foot is lifted, the front

[Illustration: Fig. 1, Fig. 2, Fig. 3 -- Forming the Skis]

of the ski will be raised. Tack on a piece of sheepskin or deer
hide where the foot rests, Fig. 4.

The best finish for skis is boiled linseed oil. After two or three

[Illustration: Fig. 4 -- The Toe Straps]

applications the under side will take a polish like glass from the
contact with the snow.

The ski-toboggan is made by placing two pairs of skis together
side by side

[Illustration: Fig. 5 -- Ski-Toboggan]

and fastening them with two bars across the top. The bars are held
with V-shaped metal clips as shown in Fig. 5.
--Contributed by Frank Scobie, Sleepy Eye, Minn.



** Homemade Life Preserver [4]

Procure an inner tube of a bicycle tire, the closed-end kind, and
fold it in four alternate sections, as shown in Fig. 1. Cut or
tear a piece of cloth into strips about 1/2 in. wide, and knot
them together. Fasten this long strip of cloth to the folded tube
and weave it alternately in and out, having each

[Illustration: Fig. 1, Fig. 2; Inner Tube and Cover]

run of the cloth about 4 in. apart, until it is bound as shown in
Fig. 1.

Make a case of canvas that will snugly fit the folded tube when
inflated. The straps that hold the preserver to the body may be
made of old suspender straps. They are sewed to the case at one
end and fastened at the other with clasps such as used on overall
straps. The tube can be easily inflated by blowing into the valve,
at the same time holding the valve stem down with the teeth. The
finished preserver is shown in Fig. 2.



** How to Make Boomerangs [4]

When the ice is too thin for skating and the snow is not right for
skis, about the only thing to do is to stay in the house. A
boomerang club will help to fill in between and also furnishes
good exercise for the muscles of the arm. A boomerang can be made

[Illustration: Bending and Cutting the Wood]

of a piece of well seasoned hickory plank. The plank is well
steamed in a wash boiler or other large kettle and then bent to a
nice curve, as shown in Fig. 1. It is held in this curve until
dry, with two pieces nailed on the sides as shown.

After the piece is thoroughly dried out, remove the side pieces
and cut it into sections with a saw, as shown in Fig. 2. The
pieces are then dressed round. A piece of plank 12 in. wide and 2
ft. long will make six boomerangs.

To throw a boomerang, grasp it and hold the same as a club, with
the hollow side away from you. Practice first at some object about
25 ft. distant, and in a short time the thrower will be able to
hit the mark over 100 ft. away. Any worker in wood can turn out a
great number of boomerangs cheaply.
--Contributed by J. E. Noble, Toronto, Ontario.



** How to Make an Eskimo Snow House [5]
By GEORGE E. WALSH

Playing in the snow can be raised to a fine art if boys and girls
will build their creations with some attempt at architectural
skill and not content themselves with mere rough work. Working in
snow and ice opens a wide field for an expression of taste and
invention, but the construction of houses and forts out of this
plastic material provides the greatest amount of pleasure to the
normally healthy boy or girl.

The snow house of the Eskimo is probably the unhealthiest of
buildings made by any savage to live in, but it makes an excellent
playhouse in winter, and represents at the same time a most
ingenious employment of the arch system in building. The Eskimos
build their snow houses without the aid of any scaffolding or
interior false work, and while there is a keystone at the top of
the dome, it is not essential to the support of the walls. These
are self-supporting from the time the first snow blocks are put
down until the last course is laid.

The snow house is of the beehive shape and the ground plan is that
of a circle. The circle is first laid out on the ground and a
space cleared for it. Then a row of snow blocks is laid on the
ground and another course of similar blocks placed on top. The
snow blocks are not exactly square in shape, but about 12 in.
long, 6 in. high and 4 or 5 in. thick. Larger or smaller blocks
can be used, according to size of the house and thickness of the
walls.

First, the snow blocks must be packed and pressed firmly into
position out of moist snow that will pack. A very light, dry snow
will not pack easily, and it may be necessary to use a little
water. If the snow is of the right consistency, there will be no
trouble in packing and working with it. As most of the blocks are
to be of the same size throughout, it will pay to make a mold for
them by forming a box of old boards nailed together, minus the
top, and with a movable bottom, or rather no bottom at all. Place
the four sided box on a flat board and ram snow in it, forcing it
down closely. Then by lifting the box up and tapping the box from
above, the block will drop out. In this way blocks of uniform size
are formed, which makes the building simpler and easier.

While one boy makes the blocks another can shave them off at the
edges and two others can build the house, one inside of the circle
and the other outside. The Eskimos build their snow houses in this
way, and the man inside stays there until he is completely walled
in. Then the door and a window are cut through the wall.

[Illustration: Laying the Snow Bricks]

[Illustration: Three-Room Snow House]

Each layer of snow blocks must have a slight slant at the top
toward the center so that the walls will constantly curve inward.
This slant at the top is obtained better by slicing off the lower
surfaces of each block before putting it in its course. The top
will then have a uniform inward slant.

The first course of the snow house should be thicker than the
others, and the thickness of the walls gradually decreases toward
the top. A wall, however, made of 6-in. blocks throughout will
hold up a snow house perfectly, if its top is no more than 6 or 7
ft. above the ground. If a higher house is needed the walls should
be thicker at the base and well up toward the middle.

The builder has no mortar for binding the blocks together, and
therefore he must make his joints smooth and even and force in
loose snow to fill up the crevices. A little experience will
enable one to do this work well, and the construction of the house
will proceed rapidly. The Eskimos build additions to their houses
by adding various dome-shaped structures to one side, and the
young architect can imitate them. Such dome-shaped structures are
shown in one of the illustrations.

A fact not well understood and appreciated is that the Eskimo
beehive snow house represents true arch building. It requires no
scaffolding in building and it exerts no outward thrust. In the
ordinary keystone arch used by builders, a, temporary structure
must be erected to hold the walls up until the keystone is fitted
in position, and the base must be buttressed against an outward
thrust. The Eskimo does not have to consider these points. There
is no outward thrust, and the top keystone is not necessary to
hold the structure up. It is doubtful whether such an arch could
be built of brick or stone without scaffolding, but with the snow
blocks it is a simple matter.



** Secret Door Lock [6]

The sketch shows the construction of a lock I have on a door which
is quite a mystery to those who do not know how it operates. It
also keeps them out. The parts of the lock on the inside of the
door are shown in Fig. 1. These parts can be covered so that no
one can see them.

[Illustration: Fig. 1, Fig. 2, Fig. 3; The Lock Parts]

The ordinary latch and catch A are attached to the door in the
usual manner. The latch is lifted with a stick of wood B, which is
about 1 ft. long and 1 in. wide, and pivoted about two-thirds of
the way from the top as shown. The latch A is connected to the
stick B with a strong cord run through a staple to secure a
right-angle pull between the pieces. A nail, C, keeps the stick B
from falling over to the left. The piece of wood, D, is 6 or 8 in.
long and attached to a bolt that runs through the door, the
opposite end being fastened to the combination dial. Two kinds of
dials are shown in Fig. 2. The piece D is fastened on the bolt an
inch or two from the surface of the door to permit placing a
spiral spring of medium strength in between as shown in Fig. 3.
The opposite end of the bolt may be screwed into the dial, which
can be made of wood, or an old safe dial will do. A nail is driven
through the outer end of the piece D and the end cut off so that
it will pass over the piece B when the dial is turned. When the
dial is pulled out slightly and then turned toward the right, the
nail will catch on the piece B and open the latch. --Contributed
by Geo. Goodbrod, Union, Ore.



** A Convenient Hot-Dish Holder [7]

When taking hot dishes from the stove, it is very convenient to
have holders handy for use. For this purpose I screwed two screw
eyes into the ceiling, one in front of the stove directly above
the place where the holder should hang, and the other back of the
stove and out of the way. I next ran a strong cord through the two
eyes. To one end of the cord I attached a weight made of a clean
lump of coal. The cord is just long enough to let the weight hang
a few inches above the floor and pass through both screw eyes. I
fastened a small ring to the other end to keep the cord from
slipping back by the pull of the weight. I then fastened two
pieces of string to the ring at the end of the cord and attached
an iron holder to the end of each string. The strings should be
just long enough to keep the holders just over the stove where
they are always

[Illustration: Holders in a Convenient Place]

ready for use, as the weight always draws them back to place.
--Contributed by R. S. Merrill, Syracuse, New York.



** Magic-Box Escape [7]

The things required to make this trick are a heavy packing box
with cover, one pair of special hinges, one or two hasps for as
many padlocks and a small buttonhook, says the Sphinx.

The hinges must be the kind for attaching inside of the box. If
ordinary butts are used, the cover of the box

[Illustration: Box with Hinges and Lock]

must be cut as much short as the thickness of the end board. The
hinges should have pins that will slip easily through the parts.

Before entering the box the performer conceals the buttonhook on
his person, and as soon as the cover is closed and locked, and the
box placed in a cabinet or behind a screen, he pushes the pin or
bolt of the hinge out far enough to engage the knob end with the
buttonhook which is used to pull the pin from the hinge. Both
hinges are treated in this manner and the cover pushed up,
allowing the performer to get out and unlock the padlocks with a
duplicate key. The bolts are replaced in the hinges, the box
locked and the performer steps out in view.



** A Flour Sifter [7]

When sifting flour in an ordinary sieve I hasten the process and
avoid the disagreeable necessity of keeping my hands in the flour
by taking the top from a small tin lard can and placing it on top
of the flour with its sharp edges down. When the sieve is shaken,
the can top will round up the flour and press it through quickly.
--Contributed by L. Alberta Norrell, Augusta, Ga.



** A Funnel [7]

An automobile horn with the bulb and reed detached makes a good
funnel. It must be thoroughly cleaned and dried after using as a
funnel.



** How to Make Comer Pieces for a Blotter Pad [8]

To protect the corners of blotting pads such as will be found on
almost every writing desk, proceed as follows:

First, make a design of a size proportionate to the size of the
pad and make a right-angled triangle, as shown in Fig. 1, on
drawing paper. Leave a small margin all around the edge and then
place some decorative form therein. Make allowance for flaps on
two sides, as shown, which may later be turned back and folded
under when the metal is worked. It should be noted that the
corners of the design are to be clipped slightly. Also note the
slight overrun at the top with the resulting V-shaped indentation.

To make a design similar to the one shown, draw one-half of it,
then fold along the center line and rub the back of the paper with
a knife handle or some other hard, smooth surface, and the other
half of the design will be traced on the second side. With the
metal shears, cut out four pieces of copper or brass of No. 22
gauge and with carbon paper trace the shape and decorative design
on the metal. Then cut out the outline and file the edges smooth.

Cover the metal over with two coats of black asphaltum varnish,
allowing each coat time to dry. Cover the back and all the face
except the white background. Immerse in a solution of 3 parts
water, 1 part nitric acid and 1 part sulphuric acid. When the
metal has been etched to the desired depth, about 1-32 of an inch,
remove it and clean off the asphaltum with turpentine. Use a stick
with a rag tied on the end for this purpose so as to keep the
solution off the hands and clothes. The four pieces should be
worked at the same time, one for each corner.

It remains to bend the flaps. Place the piece in a vise, as shown
in Fig. 2, and bend the flap sharply to a right angle. Next place
a piece of metal of a thickness equal to that of the blotter pad
at the bend and with the mallet bring the flap down parallel to
the face of the corner piece, Fig. 3. If the measuring has been
done properly, the flaps

[Illustration: Manner of Forming the Plates]

ought to meet snugly at the corner. If they do not, it may be
necessary to bend them back and either remove some metal with the
shears or to work the metal over farther. All the edges should be
left smooth, a metal file and emery paper being used for this
purpose.

If a touch of color is desired, it may be had by filling the
etched parts with enamel tinted by the addition of oil colors,
such as are used for enameling bathtubs. After this has dried,
smooth it off with pumice stone and water. To keep the metal from
tarnishing, cover it with banana-oil lacquer.



** Boring Holes in Cork [8]

The following hints will be found useful when boring holes in
cork. In boring through rubber corks, a little household ammonia
applied to the bit enables one to make a much smoother hole and
one that is nearly the same size at both openings. The common
cork, if rolled under the shoe sole, can be punctured easily and a
hole can be bored straighter. The boring is made easier by boiling
the cork, and this operation insures a hole that will he the
desired size and remain the size of the punch or bit used.



** Self-Lighting Arc Searchlight [9]

A practical and easily constructed self-lighting arc searchlight
can be made in the following manner: Procure a large can, about 6
in. in diameter, and cut three holes in its side about 2 in. from
the back end, and in the positions shown in the sketch. Two of the
holes are cut large enough to hold a short section of a garden
hose tightly, as shown at AA. A piece of porcelain tube, B, used
for insulation, is fitted tightly in the third hole. The hose
insulation A should hold the carbon F rigidly, while the carbon E
should rest loosely in its insulation.

The inner end of the carbon E is supported by a piece of No. 25
German-silver wire, C, which is about 6 in. long. This wire runs
through the

[Illustration: Arc in a Large Can]

porcelain tube to the binding post D. The binding post is fastened
to a wood plug in the end of the tube. The tube B is adjusted so
that the end of the carbon E is pressing against the carbon F. The
electric wires are connected to the carbon F and the binding post
D. A resistance, R, should be in the line.

The current, in passing through the lamp, heats the strip of
German-silver wire, causing it to expand. This expansion lowers
the end of the carbon E, separating the points of the two carbons
and thus providing a space between them for the formation of an
arc. When the current is turned off, the German-silver wire
contracts and draws the two carbon ends together ready for
lighting again. The feed can be adjusted by sliding the carbon F
through its insulation.

A resistance for the arc may be made by running the current
through a water rheostat or through 15 ft. of No. 25 gauge
German-silver wire.
--Contributed by R. H. Galbreath, Denver, Colo.



** A Traveler's Shaving Mug [9]

Take an ordinary collapsible drinking cup and place a cake of
shaving soap in the bottom ring. This will provide a shaving mug
always ready for the traveler and one that will occupy very little
space in the grip.



** Homemade Snowshoes [9]

Secure four light barrel staves and sandpaper the outside smooth.
Take two old shoes that are extra large and cut off the tops and
heels so as to leave only the toe covering fastened to the sole.
Purchase two long book straps, cut them in two in the middle and
fasten the ends on the toe covering, as shown in Fig. 1. The
straps are used to attach the snowshoe to the regular shoe. When
buckling up the straps be sure to leave them loose enough for the
foot to work freely, Fig. 2. Fasten the barrel staves in pairs,
leaving a space of 4 in. between them as shown in Fig. 3, with
thin strips of wood. Nail the old shoe soles to crosspieces

[Illustration: Made from Barrel Staves]

placed one-third of the way from one end as shown. --Contributed
by David Brown, Kansas City, Mo.



** Fish Signal for Fishing through Ice [10]

Watching a fish line set in a hole cut in the ice on a cold day is
very disagreeable, and the usual method is to

[Illustration: Bell and Battery in a Box]

have some kind of a device to signal the fisherman when a fish is
hooked. The "tip ups" and the "jumping jacks" serve their purpose
nicely, but a more elaborate device is the electric signal. A
complete electric outfit can be installed in a box and carried as
conveniently as tackle.

An ordinary electric bell, A, Fig. 1, having a gong 2-1/2 in. in
diameter, and a pocket battery, B are mounted on the bottom of the
box. The electric connection to the bell is plainly shown. Two
strips of brass, C, are mounted on the outside of the box. The
brass strips are shaped in such a way as to form a circuit when
the ends are pulled together. The box is opened and set on the ice
near the fishing hole. The fish line is hung over a round stick
placed across the hole and then tied to the inside strip of brass.
When the fish is hooked the line will pull the brass points into
contact and close the electric circuit.



** Homemade Floor Polisher [10]

A floor polisher is something that one does not use but two or
three times a year. Manufactured polishers come in two sizes, one
weighing 15 lb., which is the right weight for family use, and one
weighing 25 lb.

A polisher can be made at home that will do the work just as well.
Procure a wooden box such as cocoa tins or starch packages are
shipped in and stretch several thicknesses of flannel or carpet
over the bottom, allowing the edges to extend well up the sides,
and tack smoothly. Make a handle of two stout strips of wood, 36
in. long, by joining their upper ends to a shorter crosspiece and
nail it to the box. Place three paving bricks inside of the box,
and the polisher will weigh about 16 lb., just the right weight
for a woman to use. The polisher is used by rubbing with the grain
of the wood.
--Contributed by Katharine D. Morse, Syracuse, N. Y.



** Tying Paper Bag to Make a Carrying Handle [10]

In tying the ordinary paper bag, the string can be placed in the
paper in such a way that it will form a handle to carry the
package, and also prevent any leakage of the contents. The bag
must be long enough for the end to fold over as shown in Fig. 1.
The folds are made over the string, as in

[Illustration: Stages in Tying a Bag]

Fig. 2. The string is then tied, Fig. 3, to form a handle, Fig. 4.
--Contributed by James M. Kane, Doylestown, Pa.



** Equilibrator for Model Aeroplanes [11]

On one of my model aeroplanes I placed an equilibrator to keep it
balanced. The device was attached to a crosspiece fastened just
below the propeller between the main frame uprights. A stick was
made to swing on a bolt in the center of the crosspiece to which
was attached a weight at the lower end and two lines connecting
the ends of the planes at the upper end. These are shown in Fig.
1. When the aeroplane tips, as

[Illustration: Warping the Aeroplane Wings]

shown in Fig. 2, the weight draws the lines to warp the plane so
it will right itself automatically.
--Contributed by Louis J. Day, Floral Park, N. Y.



** Repairing Christmas-Tree Decorations [11]

Small glass ornaments for Christmas tree decorations are very
easily broken on the line shown in the sketch. These can be easily
repaired by inserting in the neck a piece of match, toothpick or
splinter of wood and tying the hanging string to it.

[Illustration: Repaired Decoration]



** Homemade Scroll Saw [11]

A scroll saw, if once used, becomes indispensable in any home
carpenter chest, yet it is safe to say that not one in ten
contains it. A scroll saw is much more useful than a keyhole saw
for sawing small and irregular holes, and many fancy knick-knacks,
such as brackets, bookracks and shelves can be made with one.

A simple yet serviceable scroll saw frame can be made from a piece
of cold-rolled steel rod, 3/32 or 1/4 in. in diameter, two 1/8-in.
machine screws, four washers and four square nuts. The rod should
be 36 or 38 in. long, bent as shown in Fig. 1. Place one washer on
each screw and put the screws through the eyelets, AA, then place
other washers on and fasten in place by screwing one nut on each
screw, clamping the washers against the frame as tightly as
possible. The saw, which can be purchased at a local hardware
store, is fastened between the clamping nut and another nut as
shown in Fig. 2.

[Illustration: Frame Made of a Rod]

If two wing nuts having the same number and size of threads are
available, use them in place of the outside nuts. They are easier
to turn when inserting a saw blade in a hole or when removing
broken blades.
--Contributed by W. A. Scranton, Detroit, Michigan.



** How to Make a Watch Fob [12]

The fixtures for the watch fob shown--half size--may be made of
either brass, copper, or silver. Silver is the most desirable but,
of course, the most expensive. The buckle is to be purchased. The
connection is to be of leather of a color to harmonize with that
of the fixtures. The body of the fob may be of leather of suitable
color or of silk. Of the leathers, green and browns are the most
popular, though almost any color may be obtained.

Make full size drawings of the outline and design of the fixtures.
With carbon paper trace these on the metal. Pierce the metal of
the parts that are to be removed with a small hand drill to make a
place for the leather or silk. With a small metal saw cut out
these parts and smooth up the edges, rounding them slightly so
they will not cut the leather or silk. Next cut out the outlines
with the metal shears. File these edges, rounding and smoothing
with emery paper. The best way of handling the decorative design
is to etch it and, if copper or brass, treat it with color.

For etching, first cover the metal with black asphaltum varnish,
on the back and all the parts that are not to be touched with the
acid. In the design shown, the unshaded parts should not be etched
and should, therefore, be covered the same as the back. Apply two
coats, allowing each time to dry, after which immerse the metal in
a solution prepared as follows: 3 parts water, 1 part nitric acid,
1 part sulphuric acid. Allow the metal to remain in this until the
acid has eaten to a depth of 1/32 in., then remove it and clean in
a turpentine bath, using a swab and an old stiff brush. The amount
of time required to do the etching will depend upon the strength
of the liquid, as well as the depth of etching desired.

[Illustration: Watch Fob]

For coloring silver, as well as brass and copper, cover the metal
with a solution of the following: 1/2 pt. of water in which
dissolve, after breaking up, five cents worth of sulphureted
potassium. Put a teaspoonful of this into a tin with 2 qt. of
water. Polish a piece of scrap metal and dip it in the solution.
If it colors the metal red, it has the correct strength. Drying
will cause this to change to purple. Rub off the highlights,
leaving them the natural color of the metal and apply a coat of
banana-oil lacquer.



** An Austrian Top [12]

All parts of the top are of wood and they are simple to make. The
handle is a piece of pine, 5-1/4 in. long, 1-1/4 in. wide and 3/4
in. thick. A handle, 3/4 in. in diameter, is formed on one end,
allowing only 1-1/4 in. of the other end to remain rectangular in
shape. Bore a 3/4-in. hole in this end for the top. A 1/16-in.
hole is bored in the edge to enter the large hole as shown. The
top can be cut from a broom handle or a round stick of hardwood.

[Illustration: Parts of the Top]

To spin the top, take a piece of stout cord about 2 ft. long, pass
one end through the 1/16-in. hole and wind it on the small part of
the top in the usual way, starting at the bottom and winding
upward. When the shank is covered, set the top in the 3/4-in.
hole. Take hold of the handle with the left hand and the end of
the cord with the right hand, give a good quick pull on the cord
and the top will jump clear of the handle and spin vigorously.
--Contributed by J.F. Tholl, Ypsilanti, Michigan.



** Pockets for Spools of Thread [13]

A detachable pocket for holding thread when sewing is shown
herewith. The dimensions may be varied to admit any number or size
of spools. Each pocket is made to take a certain size spool, the
end of the thread being run through the cloth front for obtaining
the length for threading a needle. This will keep the thread from
becoming tangled and enable it always to be readily drawn out to
the required length.
--Contributed by Miss L. Alberta Norrell, Augusta, Ga.

[Illustration: Pockets for Thread]



** Cleaning Leather on Furniture [13]

Beat up the whites of three eggs carefully and use a piece of
flannel to rub it well into the leather which will become clean
and lustrous. For black leathers, some lampblack may be added and
the mixture applied in the same way.



** A Baking Pan [13]

When making cookies, tarts or similar pastry, the housewife often
wishes for something by which to lift the baked articles from the
pan. The baking tray or pan shown in the sketch not only protects
the hands from burns but allows the baked articles easily to slip
from its surface. The pan is made from a piece of sheet iron
slightly larger than the baking space desired. Each end of the
metal is cut so that a part may be turned up and into a roll to
make handles for the pan.

[Illustration: Baking Pan without Sides]

A wire or small rod is placed between the handles as shown. This
wire is fastened at each end and a loop made in the center. The
pan can be removed from the oven by placing a stick through the
loop and lifting it out without placing the hands inside the hot
oven. The baking surface, having no sides, permits the baked
articles to be slid off at each side with a knife or fork. --A. A.
Houghton, Northville, Mich.



** A Broom Holder [13]

[Illustration: Broom Holder]

A very simple and effective device for holding a broom when it is
not in use is shown in the sketch. It is made of heavy wire and
fastened to the wall with two screw eyes, the eyes forming
bearings for the wire. The small turn on the end of the straight
part is to hold the hook out far enough from the wall to make it
easy to place the broom in the hook. The weight of the broom keeps
it in position.
--Contributed by Irl Hicks, Centralia, Mo.



**Stringing Wires [13]

A string for drawing electric wires into bent fixtures can be
easily inserted by rolling it into a small ball and blowing it
through while holding one end.



** A Darkroom Lantern [14]

Procure an ordinary 2-qt. glass fruit jar, break out the porcelain
lining in the cover and cut a hole through the metal, just large
enough to fit over the socket of an incandescent electric globe,
then solder cover and socket together, says Studio Light. Line the
inside of the jar with two thicknesses of good orange post office
paper. The best lamp for the purpose is an 8-candlepower showcase
lamp, the same as shown in the illustration. Screw the lamp into
the socket and screw the cover onto the jar, and you have a safe
light of excellent illuminating power.

When you desire to work by white light, two turns will remove the
jar.

[Illustration: Darkroom Lantern]

If developing papers are being worked, obtain a second jar and
line with light orange paper, screw into the cover fastened to the
lamp and you have a safe and pleasant light for loading and
development. By attaching sufficient cord to the lamp, it can be
moved to any part of the darkroom, and you have three lamps at a
trifling cost.



** Preventing Vegetables from Burning in a Pot [14]

Many housekeepers do not know that there is a simple way to
prevent potatoes from burning and sticking to the bottom of the
pot. An inverted pie pan placed in the bottom of the pot avoids
scorching potatoes. The water and empty space beneath the pan
saves the potatoes. This also makes the work of cleaning pots
easier as no adhering parts of potatoes are left to be scoured
out.



** A Clothes Rack [14]

A clothes-drying rack that has many good features can be made as
shown in the illustration. When the rack is

[Illustration: Folding Clothes Rack]

closed it will fit into a very small space and one or more wings
can be used at a time as the occasion or space permits, and not
tip over. The rack can be made of any hard wood and the material
list is as follows:

1 Center post. 1-1/4 in. square by 62 in. 4 Braces. 1-1/4 in.
square by 12 in. 16 Horizontal bars. 1 by 1-1/4 by 24 in. 4
Vertical pieces. 1/4 by 1 by 65 in.

Attach the four braces for the feet with finishing nails after
applying a good coat of glue.

The horizontal bars are fastened to the vertical pieces with
rivets using washers on both sides. The holes are bored a little
large so as to make a slightly loose joint. The other ends of the
bars are fastened to the center post with round head screws. They
are fastened, as shown in the cross-section sketch, so it can be
folded up.
--Contributed by Herman Fosel, Janesville, Wis.



** Homemade Shower Bath [15]

[Illustration: A Shower Bath That Costs Less Than One Dollar to
Make]

While in the country during vacation time, I missed my daily bath
and devised a shower bath that gave complete satisfaction. The
back porch was enclosed with sheeting for the room, and the
apparatus consisted of a galvanized-iron pail with a short nipple
soldered in the center of the bottom and fitted with a valve and
sprinkler. The whole, after filling the pail with water, was
raised above one's head with a rope run over a pulley fastened to
the roof of the porch, and a tub was used on the floor to catch
the water. A knot should be tied in the rope at the right place,
to keep it from running out of the pulley while the pail is
lowered to be filled with water, and a loop made in the end, which
is placed over a screw hook turned into the wall. If the loop is
tied at the proper place, the pail will be raised to the right
height for the person taking the shower bath.

The water will run from 10 to 15 minutes. The addition of some hot
water will make a splendid shower bath.
--Contributed by Dr. C. H. Rosenthal, Cincinnati, O.



** How to Make Small Sprocket Wheels [15]

As I needed several small sprocket wheels and had none on hand, I
made them quickly without other expense than the time required,
from scrap material. Several old hubs with the proper size bore
were secured. These were put on an arbor and turned to the size of
the bottom of the teeth. Hole were drilled and tapped to
correspond to the number of teeth required and old stud bolts
turned into them. The wheels were again placed on the arbor and
the studs turned to the required size. After rounding the ends of
the studs, the sprockets were ready for use and gave perfect
satisfaction.
--Contributed by Charles Stem, Phillipsburg, New York.



** Pot-Cover Closet [16]

The sides of the cover closet are cut as shown in Fig. 1 and
shelves are nailed between them at a slight angle.

[Illustration: FIG. 1  FIG. 2  Closet for Holding Pot Covers]

No dimensions are given as the space and the sizes of the covers
are not always the same. The back is covered with thin boards
placed vertically. The front can be covered with a curtain or a
paneled door as shown.
--Contributed by Gilbert A. Wehr, Baltimore, Md.



** Aid in Mixing Salad Dressing [16]

Some cooks find it a very difficult matter to prepare salad
dressing, principally mayonnaise dressing, as the constant
stirring and pouring of oil and liquids are required in the
operation. The simple homemade device shown in the accompanying
sketch greatly assists

[Illustration: Bottle in Stand]

in this work. It consists of a stand to hold a bottle, the mouth
of which rests against a. small gate directly in the rear of the
attached tin trough. The weight of the bottle and the contents
against the gate serves as a check or stopper. If the gate is
raised slightly, it will permit a continuous flow of liquid of the
desired amount.



** Saving Overexposed Developing Prints [16]

In using developing papers, either for contact printing or
enlargements, you are, by all rules of the game, entitled to a
certain number of overexposed prints, says a correspondent of
Camera Craft. But there is no reason why you should lose either
the paper or the time and trouble expended in making these prints.
By using the following method, you can turn these very dark prints
into good ones.

First: these overexposed prints must be fully developed. Do not
try to save them by rushing them out of the developer into the
short-stop or fixing bath. The results will be poor, and, if you
try to tone them afterward, the color will be an undesirable,
sickly one. Develop them into strong prints, thoroughly fix, and
wash until you are sure all hypo is removed. In my own practice, I
carry out this part of the work thoroughly, then dry the prints
and lay aside these dark ones until there is an accumulation of a
dozen or more, doing this to avoid too frequent use of the very
poisonous bleaching solution. The bleacher is made up as follows
and should be plainly marked "Poison."

    Cyanide of potassium ....... 2 oz.
    Iodide of potassium ....... 20 gr.
    Water ..................... 16 oz.

Place the dry print, without previous wetting, in this solution.
It will bleach slowly and evenly, but, when it starts to bleach,
transfer it to a tray of water, where it will continue to bleach.
When the desired reduction has taken place, stop the action at
once by immersing the print in a 10-per-cent solution of borax.
The prints may be allowed to remain in this last solution until
they are finished. A good final washing completes the process.
This washing must be thorough and a sponge or a tuft of cotton
used to clean the surface of the print.

With a little practice, this method of saving prints that are too
dark becomes easy and certain. The prints are lightened and at the
same time improved in tone, being made blue-black with a delicate
and pleasing quality that will tempt you to purposely overexpose
some of your prints in order to tone them by this method for
certain effects. The process is particularly valuable to the
worker in large sizes, as it provides a means of making quite a
saving of paper that would otherwise be thrown away.



** An Ironing-Board Stand [17]

An ordinary ironing board is cut square on the large end and a
slot cut 1-1/2 in. wide and 4 in. long to admit the angle support.
The support is placed against the table and the board

[Illustration: Stand Attached to Table]

is pressed down against the outer notch which jams against the
table, thus holding the board rigid and in such a position as to
give free access for ironing dresses, etc.
--Contributed by T. L. Gray, San Francisco, Cal.



** A Desk Blotting Pad [17]

Procure four sheets of blotting paper, preferably the colored
kind, as it will appear clean much longer than the white. The size
of the pad depends on the size of the blotting paper.

Fold four pieces of ordinary wrapping paper, 5 by 15 in. in size,
three times, to make it 5 by 5 in. Fold each one from corner to
corner as shown in Fig. 1 and again as in Fig. 2. Paste the last
fold together and the corner holders are complete. Put one on each
corner of the blotting paper. They can be fastened with a small
brass paper fastener put through the top of the holder. The
blotting paper can

[Illustration: Fig. 1, 2, 3 Paper Corners for Blotter Pads]

be easily changed by removing the holders and fasteners. Corners
complete are shown in Fig. 3.
--Contributed by J. Wilson Aldred Toronto, Canada.



** Sleeve Holders for Lavatories [17]

A very handy article is an attachment on wash basins or lavatories
for holding the sleeves back while washing the hands. It is very
annoying to have the sleeves continually slip down and become wet
or soiled. The simple device shown herewith can be made with bent
wires or hooks and attached in such a way that it can be dropped
out

[Illustration: Wires Attached to a Lavatory]

of the way when not in use.
--Contributed by L.J. Monahan, Oshkosh, Wisconsin.



** Removing Tarnish [17]

A pencil eraser will remove the tarnish from nickel plate, and the
ink eraser will remove the rust from drawing instruments.



** How to Make a Brass Bookmark [18]

Secure a piece of brass of No. 20 gauge, having a width of 2-1/4
in. and a length of 5 in. Make a design similar to that shown, the
head of which is 2 in. wide, the shaft 1 in. wide below the

[Illustration: FIG. 1 Fig. 2 The Pattern and the Finished
Bookmark]

head and the extreme length 4-1/2 in. Make one-half of the design,
as shown in Fig. 1, freehand, then trace the other half in the
usual way, after folding along the center line. Trace the design
on the metal, using carbon paper, which gives the outline of the
design Fig. 2.

With the metal shears, cut out the outline as indicated by the
drawing. With files, smooth off any roughness

[Illustration: Drilling and Sawing the Metal]

and form the edge so that it shall be nicely rounded.

The parts of the design in heavy color may be treated in several
ways. A very satisfactory treatment is obtained by etching, then
coloring. Clean the metal thoroughly with pumice stone and water
or with alcohol before the design is applied. Cover all the metal
that is not to be lowered with a thick coating of asphaltum. Allow
this to dry, then put on a second coat. After this has dried,
thoroughly immerse the metal in a solution composed as follows: 3
parts water, 1 part sulphuric acid, 1 part nitric acid.

Allow the metal to remain in this solution until the exposed part
has been eaten about 1/32 in. deep, then remove it and clean off
the asphaltum, using turpentine. Do not put the hands in the
solution, but use a swab on a stick.

For coloring olive green, use 2 parts water to 1 part permuriate
of iron. Apply with a small brush.

The lines at A and B will need to be cut, using a small metal saw.
Pierce a hole with a small drill, Fig. 3, large enough to receive
the saw and cut along the lines as in Fig. 4. A piece of wood with
a V-shaped notch which is fastened firmly to the bench forms the
best place in which to do such sawing. The teeth of the saw should
be so placed that the sawing will be done on the downward stroke.
The metal must be held firmly, and the saw allowed time to make
its cut, being held perpendicular to the work.

After the sawing, smooth the edges of the metal with a small file
and emery paper. The metal clip may be bent outward to do this
part of the work.



** Cheesebox-Cover Tea Tray [18]

The cover from a cheesebox can be converted into a tea tray that
is very dainty for the piazza, or for serving an invalid's
breakfast.

First sandpaper the wood until it is smooth, then stain it a
mahogany color. The mahogany stain can be obtained ready prepared.
After the stain has dried, attach brass handles, which can be
obtained for a small sum at an upholsterer's shop. A round
embroidered doily in the bottom adds to the appearance of the
tray.
--Contributed by Katharine D. Morse, Syracuse, New York.



** Piercing-Punch for Brass [19]

Drill a 1/2-in. hole through a block of pine or other soft wood 2
in. thick. Tack over one end of the hole a piece of pasteboard in
which seven coarse sewing-machine needles have been inserted. The
needles should be close together and pushed through the pasteboard
until the points show. The hole is then filled with melted babbitt
metal. When this is cold, the block is split and the pasteboard
removed. This tool makes neat pierced work and in making brass
shades, it does the work rapidly.
--Contributed by H. Carl Cramer, East Hartford, Conn.



** Kitchen Chopping Board [19]

Cooks can slice, chop or mince vegetables and various other food
rapidly by placing the little device, as shown, on a chopping
board. Ii is an ordinary staple, driven in just far enough to
allow a space for the end of an ordinary pointed kitchen knife to
fit in it. The staple is driven in the edge of the chopping board.
The knife can be raised and lowered with one hand, as

[Illustration: Knife Attached to the Board]

the material is passed under the blade with the other. Great
pressure can be applied and the knife will not slip. --Contributed
by M. M. Burnett, Richmond, Cal.



** Carrying Mattresses [19]

Sew straps to the sides of mattresses and they can be handled much
easier.



** A Carpenter's Gauge [19]

The home workshop can be supplied with a carpenter's gauge without
any expense by the use of a large spool and

[Illustration: Round Stick In a Spool]

a round stick of wood. The stick should be dressed to fit the hole
in the spool snugly and a small brad driven through one end so
that the point will protrude about 1/16 in.

The adjustment of the gauge is secured by driving the stick in the
hole in the direction desired. A better way and one that will make
the adjusting easy is to file the point end of a screw eye flat
and use it as a set screw through a hole in the side of the spool.



** A Flatiron Rest [19]

The iron rest and wall hanger shown in the sketch is made of sheet
iron. The upturned edges of the metal are

[Illustration: Board or Wall Iron Rest]

bent to fit the sloping sides of the iron. The holder and iron can
be moved at the same time.
--Contributed by W. A. Jaquythe, Richmond, Cal.



** Use for Paper Bags [19]

When groceries are delivered, save the paper bags and use them for
staring bread and cakes. Tie the neck of the bag with a string and
it will keep the contents fresh and clean.
--Contributed by Mrs. L. H. Atwell, Kissimmee, Florida.



** Use Chalk on Files [19]

If a little chalk is rubbed on a file before filing steel, it will
keep the chips from sticking in the cuts on the file and
scratching the work.



** A Homemade Steam Turbine [20]
By WILLIAM H. WARNECKE

Procure some brass, about 3/16 in. thick and 4 in. square; 53
steel pens, not over 1/4 in. in width at the shank; two enameled,
or tin, saucers or pans, having a diameter on the inside part of
about 4-1/2 in.; two stopcocks with 1/8 in. holes; one shaft; some
pieces of

[Illustration: Details of Turbine]

brass, 1/4 in. thick, and several 1/8-in. machine screws.

Lay out two circles on the 3/16-in. brass, one having a diameter
of 3-1/2 in. and the other with a diameter of 2-3/4 in. The
outside circle is the size of the finished brass wheel, while the
inside circle indicates the depth to which the slots are to be
cut. Mark the point where a hole is to be drilled for the shaft,
also locate the drill holes, as shown at A, Fig. 1. After the
shaft hole and the holes A are drilled in the disk, it can be used
as template for drilling the side plates C.

The rim of the disk is divided into 53 equal parts and radial
lines drawn from rim to line B, indicating the depth of the slots.
Slots are cut in the disk with a hacksaw on the radial lines. A
small vise is convenient for holding the disk while cutting the
slots.

When cutting the disk out of the rough brass, sufficient margin
should be left for filing to the true line. The slots should be
left in their rough state as they have a better hold on the pens
which are used for the blades. The pens are inserted in the slots
and made quite secure by forcing ordinary pins on the inside of
the pens and breaking them off at the rim, as shown in Fig. 4.

When the pens are all fastened two pieces of metal are provided,
each about 1 in. in diameter and 1/32 in. thick, with a 3/8-in.
hole in the center, for filling pieces which are first placed
around the shaft hole between the disk and side plates C, Fig. 1.
The side plates are then secured with some of the 1/8-in. machine
screws, using two nuts on each screw. The nuts should be on the
side opposite the inlet valves. The shaft hole may also be filed
square, a square shaft used, and the ends filed round for the
bearings.

The casing for the disk is made of two enameled-iron saucers, Fig.
2, bolted together with a thin piece of asbestos between them to
make a tight joint. A 3/4-in. hole is cut near the edge of one of
the saucers for the exhaust. If it is desired to carry the exhaust
beyond the casing, a thin pipe can be inserted 1/4 in. into the
hole. Holes are drilled through the pipe on both inside and
outside of the casing, and pins inserted, as shown in Fig. 5.
Solder is run around the outside pin to keep the steam from
escaping. At the lowest point of the saucer or casing a 1/8-in.
hole is drilled to run off the water. A wood plug will answer for
a stopcock.

If metal dishes, shaped from thick material with a good coating of
tin, can be procured, it will be much easier to construct the
casing than if enameled ware is used. The holes can be easily
drilled and the parts fitted together closely. All seams and
surfaces around fittings can be soldered.

Nozzles are made of two stopcocks having a 1/8-in. hole. These are
connected to a 3/8-in. supply pipe. The nozzles should be set at
an angle of 20 deg. with the face of the disk. The nozzle or
stopcock will give better results if the discharge end is filed
parallel to the face of the disk when at an angle of 20 deg. There
should be a space of 1/16 in. between the nozzle and the blades to
allow for sufficient play, Fig. 3.

The bearings are made of 1/4-in. brass and bolted to the casing,
as shown, with 1/8-in. machine screws and nuts. Two nuts should be
placed on each screw. The pulley is made by sliding a piece of
steel pipe on the engine shaft and fastening it with machine
screws and nuts as shown in Fig. 6. If the shaft is square, lead
should be run into the segments.

The driven shaft should have a long bearing. The pulley on this
shaft is made of pieces of wood nailed together, and its
circumference cut out with a scroll saw. Flanges are screwed to
the pulley and fastened to the shaft as shown in Fig. 7.

The bearings are made of oak blocks lined with heavy tin or sheet
iron for the running surface. Motion is transmitted from the
engine to the large pulley by a thin but very good leather belt.



** Homemade Telegraph Key [21]

A simple and easily constructed telegraph key may be made in the
following manner: Procure a piece of sheet brass, about 1/32 in.
thick, and cut out a strip 3-1/2 in. long by 3/4 in. wide. Bend as
shown in Fig. 1 and drill a hole for the knob in one end and a
hole for a screw in the other. Procure a small wood knob and
fasten it in place with a small screw. Cut a strip of the same
brass 2-3/4 in. long and 5/16 in. wide and bend as shown in Fig.
2. Drill two holes in the feet for screws to fasten it to the
base, and one hole in the top part for a machine screw, and solder
a small nut on the under side of the metal over the hole.

Mount both pieces on a base 4-1/4 by 2-3/4 by 1/4 in., as in Fig.
3, and where

[Illustration: Brass Key on a Wood Base]

the screw of the knob strikes the base when pressed down, put in a
screw or brass-headed tack for a contact. Fasten the parts down
with small brass wood-screws and solder the connections beneath
the base. Binding posts from an old battery cell are used on the
end of the base. The screw on top of the arch is used to adjust
the key for a long or short stroke.
--Contributed by S. V. Cooke, Hamilton, Canada.



** Keeping Food Cool in Camps [21]

Camps and suburban homes located where ice is hard to get can be
provided with a cooling arrangement herein described that will
make a good substitute for the icebox. A barrel is sunk in the
ground in a shady place, allowing plenty of space about the
outside to fill in with gravel. A quantity of small stones and
sand is first put in wet. A box is placed in the hole over the top
of the barrel and filled in with clay or earth well tamped. The
porous condition of the gravel drains the surplus water after a
rain.

The end of the barrel is fitted with a light cover and a heavy
door hinged to the box. A small portion of damp sand is sprinkled
on the bottom of the barrel. The covers should be left open
occasionally to prevent mold and to remove any bad air that may
have collected from the contents.
--Contributed by F. Smith, La Salle, Ill.



** Homemade Work Basket [22]

Secure a cheese box about 12 in. high and 15 in. or more in
diameter. It will pay you to be careful in selecting this box. Be
sure to have the cover. Score the wood deeply with a carpenter's
gauge inside and out 3-1/2 in. from the top of the box. With
repeated scoring the wood will be almost cut through or in shape
to finish the cut with a knife. Now you will have the box in two
pieces. The lower part, 8-1/2 in. deep over all, we will call the
basket, and the smaller part will be known as the tray.

Remove the band from the cover and cut the boards to fit in the
tray flush with the lower edge, to make the bottom. Fasten with
3/4-in brads. The kind of wood used in making these boxes cracks
easily and leaves a rough surface which should be well
sandpapered.

The four legs are each 3/4-in. square and 30-1/2 in. long. The
tops should be beveled to keep them from splintering at the edges.
With a string or tape measure, find the circumference of the tray
or basket and divide this into four equal parts, arranging the lap
seam on both to come midway between two of the marks. When
assembling, make these seams come between the two back legs.

The tray is placed 1-1/4 in. from the top end and the basket 6-3/4
in. from the bottom end of the legs. Notch the legs at the lower
point about 1/8 in. deep and 1-1/4 in. wide to receive the band at
the lower end of the basket. Fasten with 3/4-in. screws, using
four to each leg, three of which are in the basket. Insert the
screws from the inside of the box into the legs.

Stain the wood before putting in the

[Illustration: Work Basket]

lining. If all the parts are well sandpapered, the wood will take
the stain nicely: Three yards of cretonne will make a very
attractive lining. Cut two sheets of cardboard to fit in the
bottom of the tray and basket. Cover them with the cretonne,
sewing on the back side. Cut four strips for the sides from the
width of the goods 5-1/2 in. wide and four strips 10 in. wide. Sew
them end to end and turn down one edge to a depth of 1 in. and
gather it at that point, also the lower edge when necessary. Sew
on to the covered cardboards. Fasten them to the sides of the tray
and basket with the smallest upholsterers' tacks. The product of
your labor will be a very neat and useful piece of furniture.
--Contributed by Stanley H. Packard, Boston, Mass.



** A Window Display [22]

A novel and attractive aeroplane window display can be easily made
in the following manner: Each aeroplane is cut from folded paper,
as shown in the sketch, and the wings bent out on the dotted
lines. The folded part in the center is pasted together. Each
aeroplane is fastened with a small thread from the point A as
shown. A figure of an airman can be pasted to each aeroplane. One
or more of the aeroplanes can be fastened in the blast of an
electric fan and kept in flight the same as a kite. The fan can be
concealed to make the display more real. When making the display,
have the background of such

[Illustration: Paper Aeroplanes in Draft]

a color as to conceal the small threads holding the aeroplanes.
--Contributed by Frederick Hennighausen, Baltimore, Md.



** How to Make a Flint Arrowhead [23]

If you live where flints abound, possess the requisite patience
and the knack of making things, you can, with the crudest of tools
and a little practice, chip out as good arrowheads as any painted
savage that ever drew a bow.

Select a piece of straight-grained flint as near the desired shape
as possible. It may be both longer and wider than the finished
arrow but it should not be any thicker. The side, edge and end
views of a suitable fragment are shown in Fig. 1. Hold the piece
with one edge or end resting on a block of wood and strike the
upper edge lightly with a hammer, a small boulder or anything that
comes handy until the piece assumes the shape shown in Fig. 2.

[Illustration: Fig.2  Fig.3  The Stone Chipped into Shape]

The characteristic notches shown in the completed arrow, Fig. 3,
are chipped out by striking the piece lightly at the required
points with the edge of an old hatchet or a heavy flint held at
right angles to the edge of the arrow. These heads can be made so
that they cannot be distinguished from the real Indian arrowheads.
--Contributed by B. Orlando Taylor, Cross Timbers, Mo.



** An Opening Handle for a Stamp Pad [23]

A stamp pad is a desk necessity and the cleanliness of one depends
on keeping it closed when it is not in use. The opening and
closing of a pad requires both hands and consequently the closing
of a pad is often neglected in order to avoid soiling the fingers.
This trouble can be avoided if the pad is fitted with a small
handle as shown in the sketch. Take the ordinary pad and work the
hinge until it opens freely.

[Illustration: Handle on Cover]

If necessary apply a little oil and spread the flanges of the
cover slightly.

Saw off the top of a common wood clothespin just above the slot,
saving all the solid part. Fasten this to the cover near the back
side in an upright position with a screw. A tap on the front side
of the pin will turn it over backward until the head rests on the
desk thus bringing the cover up in the upright position. When
through using the pad, a slight tap on the back side of the cover
will turn it down in place.
--Contributed by H. L. Crockett, Gloversville, N. Y.



** Concrete Kennel [23]

The kennel shown in the illustration is large enough for the usual
size of dog. It is cleanly, healthful and more ornamental than the
average kennel.

[Illustration: Finished Kennel]

This mission style would be in keeping with the now popular
mission and semi-mission style home, and, with slight
modifications, it could be made to conform with the ever beautiful
colonial home. It is not difficult to

[Illustration: Concrete Forms]

build and will keep in good shape for many years. The dimensions
and the manner of making the forms for the concrete, and the
location for the bolts to hold the plate and rafters, are shown in
the diagram.
--Contributed by Edith E. Lane, El Paso, Texas.



** Nutshell Photograph Novelty [24]

Split an English walnut in the center, remove the contents, and
scrape out the rough parts. Make an oval

[Illustration: Photograph in the Shell]

opening by filing or grinding. If a file is used, it should be new
and sharp. After this is done, take a small half round file and
smooth the edges into shape and good form.

The photograph print should be quite small--less than 1/2 in.
across the face. Trim the print to a size a little larger than the
opening in the shell, and secure it in place with glue or paste.
It may be well to fill the shell with cotton. Mount the shell on a
small card with glue, or if desired, a mount of different shape
can be made of burnt woodwork.
--Contributed by C. S. Bourne, Lowell, Mass.



** Spoon Holder on a Kettle [24]

In making marmalade and jellies the ingredients must be stirred
from time to time as the cooking proceeds. After stirring, some of
the mixture always remains on the spoon. Cooks often lay the spoon
on a plate or stand it against the cooking utensil with the handle
down. Both of these methods are wasteful. The accompanying
illustration shows a device made of sheet copper to hold the spoon
so that the drippings will return to the cooking utensil. The
copper is not hard to bend and it can be shaped so that the device
can be used on any pot or kettle.
--Contributed by Edwin Marshall, Oak Park, Ill.

[Illustration: Spoon Holder]



** Repairing Cracked Gramophone Records [24]

Some time ago I received two gramophone records that were cracked
in shipment but the parts were held together with the paper label.
As these were single-faced disk records, I used the following
method to stick them together: I covered the back of one with
shellac and laid the two back to back centering the holes with the
crack in one running at right angles to the crack in the other.
These were placed on a flat surface and a weight set on them.
After several hours' drying, I cleaned the surplus shellac out of
the holes and played them.

As the needle passed over the cracks the noise was hardly audible.
These records have been played for a year and they sound almost as
good as new.
--Contributed by Marion P. Wheeler, Greenleaf, Oregon.



** New Use for a Vacuum Cleaner [25]

An amateur mechanic who had been much annoyed by the insects which
were attracted to his electric lights found a solution in the
pneumatic moth trap described in a recent issue of Popular
Mechanics. He fixed a funnel to the end of the intake tube of a
vacuum cleaner and hung it under a globe. The insects came to the
light, circled over the funnel and disappeared. He captured
several pounds in a few hours.
--Contributed by Geo. F. Turl, Canton, Ill.



** Filtering with a Small Funnel [25]

In filtering a large amount of solution one usually desires some
means other than a large funnel and something to make the watching
of the process unnecessary. If a considerable quantity of a
solution be placed in a large bottle or flask, and a cork with a
small hole in it inserted in the mouth, and the apparatus
suspended in an inverted position over a small funnel so that the
opening of the cork is just below the water level in the funnel,
the filtering process goes on continuously with no overflow of the
funnel.

As soon as the solution in the funnel is below the cork, air is
let into the flask and a small quantity of new solution is let
down into the funnel. The process works well and needs no
watching, and instead of the filtrate being in a large filter
paper, it is on one small piece and can be handled with ease.
--Contributed by Loren Ward, Des Moines, Iowa.



** A Postcard Rack [25]

The illustration shows a rack for postcards. Those having houses

[Illustration: Finished Rack]

with mission-style furniture can make such a rack of the same
material as the desk, table or room furnishings and finish it in
the same manner.

The dimensions are given in the detail sketch. The two ends are
cut from 1/4-in. material, the bottom being 3/8 in. thick. Only
three pieces are required, and as they are simple in design,
anyone can cut them out with a

[Illustration: Details of the Rack]

saw, plane and pocket knife.
--Contributed by Wm. Rosenberg, Worcester, Mass.



** Substitute Shoe Horn [25]

A good substitute for a shoe horn is a handkerchief or any piece
cloth used in the following way: Allow part of the handkerchief or
cloth to enter the shoe, place the toe of the foot in the shoe so
as to hold down the cloth, and by pulling up on the cloth so as to
keep it taut around the heel the foot will slide into the shoe
just as easily as if a shoe horn were used.
--Contributed by Thomas E. Dobbins, Glenbrook, Conn.



** Building a Small Photographic Dark Room [26]

In building a photographic dark room, it is necessary to make it
perfectly light-tight, the best material to use being matched
boards. These boards are tongued and grooved and when put together
effectually prevent the entrance of light.

The next important thing to be considered is to make it
weather-tight, and as far as the sides are concerned the matched
boards will do this also, but it is necessary to cover the roof
with felt or water-proof paper.

The best thickness for the boards is 1 in., but for cheapness 3/4
in. will do as well, yet the saving is so little that the 1-in.
boards are preferable.

The dark room shown in the accompanying sketch measures 3 ft. 6
in. by 2 ft. 6 in., the height to the eaves being 6 ft. Form the
two sides shown in Fig 1, fixing the crosspieces which hold the
boards together in such positions that the bottom one will act as
a bearer for the floor, and the second one for the developing
bench. Both sides can be put together in this way, and both
exactly alike. Keep the ends of the crosspieces back from the
edges of the boards far enough to allow the end boards to fit in
against them.

One of the narrow sides can be formed in the same way, fixing the
crosspieces on to correspond, and then these three pieces can be
fastened together by screwing the two wide sides on the narrow
one.

Lay the floor next, screwing or nailing the boards to the
crosspieces, and making the last board come even with the ends of
the crosspieces, not even with the boards themselves. The single
boards can then be fixed, one on each side of what will be the
doorway, by screwing to the floor, and to the outside board of the
sides. At the top of the doorway, fix a narrow piece between the
side boards, thus leaving a rectangular opening for the door.

The roof boards may next be put on, nailing them to each other at
the ridge, and to the sides of the room at the outsides and eaves.
They should overhang at the sides and eaves about 2 in., as shown
in Figs. 3 and 4.

One of the sides with the crosspieces in place will be as shown in
Fig. 2 in section, all the crosspieces and bearers intersecting
around the room.

The door is made of the same kind of boards held together with
crosspieces, one of which is fastened so as to fit closely to the
floor when the door is hinged, and act as a trap for the light.
The top crosspiece is also fastened within 1 in. of the top of the
door for the same reason.

Light traps are necessary at the sides and top of the door. That
at the hinged side can be as shown at A, Fig. 5, the closing side
as at B, and the top as at C in the same drawing. These are all in
section and are self-explanatory. In hinging the door, three butt
hinges should be used so as to keep the joint close.

The fittings of the room are as shown sectionally in Fig. 6, but
before fixing these it is best to line the room with heavy, brown
wrapping paper, as an additional safeguard against the entrance of
light.

The developing bench is 18 in. wide, and in the middle an opening,
9 by 11 in., is cut, below which is fixed the sink. It is shown in
detail in Fig. 7, and should be zinc lined.

The zinc should not be cut but folded as shown in Fig. 8, so that
it will fit inside the sink. The bench at each side of the sink
should be fluted (Fig. 9), so that the water will drain off into
the sink. A strip should be fixed along the back of the bench as
shown in Figs. 6 and 9, and an arrangement of slats (Fig. 10),
hinged to it, so as to drop on the sink as in Fig. 6, and shown to
a larger scale in Fig. 11.

A shelf for bottles and another for plates, etc., can be fixed
above the developing bench as at D and E (Fig. 6) and another as F
in the same drawing. This latter forms the bottom of the tray
rack, which is fixed on as shown

[Illustration: Details of the Dark Rook]

in Fig. 13. The divisions of the tray rack are best fitted loosely
in grooves formed by fixing strips to the shelves and under the
bench and sink as in Fig. 13.

Extra bearing pieces will be wanted for the shelves mentioned
above, these being shown in Fig. 14. The window is formed by
cutting an opening in the side opposite the door, and fixing in it
a square of white glass with strips of wood on the inside and
putty on the outside, as in Fig. 15. A ruby glass is framed as
shown at G, Fig. 16, and arranged to slide to and fro in the
grooved runners H, which makes it possible to have white light, as
at I, or red light as at K, Fig. 16. The white glass with runners
in position is shown at L in the same drawing, but not the red
glass and frame. Ventilation is arranged for by boring a series of
holes near the floor, as at M, Fig. 6, and near the roof as at N
in the same drawing, and trapping the light without stopping the
passage of air, as shown in the sections, Fig. 17.

The finish of the roof at the gables is shown in Fig. 18, the
strip under the boards holding the felt in position when folded
under, and the same is true of the roll at the top of the roof in
Fig. 19.

The house will be much strengthened if strips, as shown in Fig.
20, are fastened in the corners inside, after lining with brown
paper, screwing them each way into the boards. The door may have a
latch or lock with a knob, but should in addition have two buttons
on the inside, fixed so as to pull it shut tightly at top and
bottom. A waste pipe should be attached to the sink and arranged
to discharge through the floor. A cistern with pipe and tap can be
fastened in the top of the dark room, if desired, or the room may
be made with a flat roof, and a tank stand on it, though this is
hardly advisable.

It is absolutely necessary that the room be well painted, four
coats at first is not too many, and one coat twice a year will
keep it in good condition.

A brick foundation should be laid so that no part of the room
touches the ground.



** The Versatile Querl [28]

"Querl" is the German name for a kitchen utensil which may be used
as an egg-beater, potato-masher or a lemon-squeezer. For beating
up an egg in a glass, mixing flour and water, or stirring cocoa or
chocolate, it is better than anything on the market.

[Illustration: Querl Made of Wood]

This utensil is made of hardwood,  preferably maple or ash. A
circular piece about 2 in. in diameter is cut from 1/2-in. stock
and shaped like a star as shown in Fig. 1, and a 3/8-in. hole
bored in the center for a handle. The handle should be at least 12
in. in length and fastened in the star as shown in Fig. 2.

In use, the star is placed in the dish containing the material to
be beaten or mixed and the handle is rapidly rolled between the
palms of the hands.
--Contributed by W. Karl Hilbrich, Erie, Pennsylvania.



** An Emergency Soldering Tool [28]

Occasionally one finds a piece of soldering to do which is
impossible to reach with even the smallest of the ordinary
soldering irons or coppers. If a length of copper wire as large as
the job will permit and sufficiently long to admit being bent at
one end to form a rough handle, and filed or dressed to a point on
the other, is heated and tinned exactly as a regular copper should
be, the work will cause no trouble on account of inaccessibility.
--Contributed by E. G. Smith, Eureka Springs, Ark.



** Smoothing Paper after Erasing [29]

When an ink line is erased the roughened surface of the paper
should be smoothed or polished so as to prevent the succeeding
lines of ink from spreading. A convenient desk accessory for this
purpose can be made of a short

[Illustration: Collar Button Ends In Wood Stick]

piece of hardwood and two bone collar buttons.

File off the head of one button at A and the base from another at
B. Bore a small hole D and E in each end of the wood handle C and
fasten the button parts in the holes with glue or sealing wax. The
handle can be left the shape shown or tapered as desired. The
small end is used for smoothing small erasures and the other end
for larger surfaces.



** A Cherry Seeder [29]

An ordinary hairpin is driven part way into a small round piece of
wood, about 3/8 in. in diameter and 2 or 2-1/2 in. long, for a
handle, as shown in the sketch. The hairpin should be a very

[Illustration: Hairpin In Stick]

small size. To operate, simply insert the wire loop into the
cherry where the stem has been pulled off and lift out the seed.
--Contributed by L. L. Schweiger, Kansas City, Mo.



** A Dovetail Joint  [29]

The illustration shows an unusual dovetail joint, which, when put
together properly is a puzzle. The tenon or tongue of the joint is
sloping on three surfaces and the mortise is cut sloping to match.
The bottom surface of the mortise is the same width at

[Illustration: Shape of Tenon and Mortise]

both ends, the top being tapering toward the base of the tongue.
--Contributed by Wm. D. Mitchell, Yonkers, New York.



** Base for Round-End Bottles [29]

The many forms of round-bottomed glass bottles used in chemical
laboratories require some special kind of support on which they
can be safely placed from time to time when the chemist

[Illustration: Base Made-of Corks]

does not, for the moment, need them. These supports should not be
made of any hard material nor should they be good conductors of
heat, as such qualities would result in frequent breakage.

A French magazine suggests making the supports from the large
corks of glass jars in which crystal chemicals are usually
supplied from the dealers. The manner of making them is clearly
shown in the sketch. Each cork is cut as in Fig. 1 and placed on a
wire ring (Fig. 2) whose ends are twisted together and the last
section of cork is cut through from the inner side to the center
and thus fitted over the wire covering the twisted ends, which
binds them together. The corks in use are shown in Fig. 3.



** Rustic Window Boxes [30]

Instead of using an ordinary green-painted window box, why not
make an artistic one in which the color does not clash with the
plants contained in it but rather harmonizes with them.

Such a window box can be made by anyone having usual mechanical
ability, and will furnish more opportunities for artistic and
original design than many other articles of more complicated
construction.

The box proper should be made a little shorter than the length of
the window to allow for the extra space taken up in trimming and
should be nearly equal in width to the sill, as shown in Fig. 1.
If the sill is inclined, as is usually the case, the box will
require a greater height in front, to make it set level, as shown
in Fig. 2.

The box should be well nailed or screwed together and should then
be painted all over to make it more durable. A number of 1/2-in.
holes should be drilled in the bottom, to allow the excess water
to run out and thus prevent rotting of the plants and box.

Having completed the bare box, it may be trimmed to suit the fancy
of the maker. The design shown in Fig. 1 is very simple and easy
to construct, but may be replaced with a panel or other design.
One form of panel design is shown in Fig. 3.

Trimming having too rough a surface will be found unsuitable for
this work as it is difficult to fasten and cannot be split as well
as smooth trimming. It should be cut the proper length before
being split and should be fastened with brads. The half-round
hoops of barrels will be found very useful in trimming, especially
for filling-in purposes, and by using them the operation of
splitting is avoided. After the box is trimmed, the rustic work
should be varnished, in order to thoroughly preserve it, as well
as improve its appearance.

[Illustration: Artistic Flower Boxes]



** Antidote for Squirrel Pest [30]

To the owner of a garden in a town where squirrels are protected
by law, life in the summer time is a vexation. First the squirrels
dig up the sweet corn and two or three replantings are necessary.
When the corn is within two or three days of being suitable for
cooking, the squirrels come in droves from far and near. They eat
all they can and carry away the rest. When the corn is gone
cucumbers, cabbages, etc., share the same fate, being partly eaten
into. At the risk of being arrested for killing the squirrels I
have used a small target rifle morning and night, but during my
absence the devastation went on steadily. Last year they destroyed
my entire corn crop. Traps do no good; can't use poison, too
dangerous. But I have solved the difficulty; it's easy.

Shake cayenne pepper over the various vegetables which are being
ruin, and observe results.



** Homemade Electric Stove [31]
By J. F. THOLL

The construction of an electric stove is very simple, and it can
be made by any home mechanic having a vise and hand drill. The
body is made of sheet or galvanized iron, cut out and drilled as
shown in Fig. 1.

Each long projection represents a leg, which is bent at right
angles on the center line by placing the metal in the jaws of a
vise and hammering the metal over flat. If just the rim is gripped
in the vise, it will give a rounding form to the lower part of the
legs. The small projections are bent in to form a support for the
bottom.

The bottom consists of a square piece of metal, as shown in Fig.
2. Holes are drilled near the edges for stove bolts to fasten it
to the bottom projections. Two of the larger holes are used for
the ends of the coiled rod and the other two for the heating-wire
terminals. The latter holes should be well insulated with
porcelain or mica. The top consists of a square piece of metal
drilled as shown in Fig. 3. Four small ears are turned down to
hold the top in place.

One end of the coiled rod is shown in Fig. 4. This illustrates how
two pins are inserted in holes, drilled at right angles, to hold
the coil on the bottom plate. The coiled rod is 3/16 in.

[Illustration: Pattern for Parts of the Electric Stove]

in diameter and 27 in. long. The rod is wrapped with sheet
asbestos, cut in 1/2-in. strips.

The length of the heating wire must be determined by a test. This
wire can be purchased from electrical stores. Stovepipe wire will
answer the purpose when regular heating wire cannot be obtained.
The wire is coiled around the asbestos-covered rod, so that no
coil will be in contact with another coil. If, by trial, the coil
does not heat sufficiently, cut some of it off and try again.
About 9-1/2 ft. of No. 26 gauge heating wire will be about right.
The connection to an electric-lamp socket is made with ordinary
flexible cord, to which is attached a screw plug for making
connections.



** Glass-Cleaning Solution [31]

Glass tumblers, tubing and fancy bottles are hard to clean by
washing them in the ordinary way, as the parts are hard to reach
with the fingers or a brush. The following solution makes an
excellent cleaner that will remove dirt and grease from crevices
and sharp corners. To 9 parts of water add 1 part of strong
sulphuric acid. The acid should be added to the water slowly and
not the water to the acid. Add as much bichromate of potash as the
solution will dissolve. More bichromate of potash should be added
as the precipitate is used in cleaning.

The chemicals can be purchased cheaply from a local drug store,
and made up and kept in large bottles. The solution can be used
over and over again. -- Contributed by Loren Ward Des Moines,
Iowa.



** Automatic-Closing Kennel Door [32]

When the neighborhood cats are retired for the night and there is
nothing more to chase, my fox terrier seems to realize that his
usefulness

[Illustration: Diagram of Closing Door]

for the day is over and begs to be put in his kennel that he may
not bark at the moon as some dogs are apt to do. This necessitates
my putting him out at a time when it may not be convenient.
Frequently in stormy weather this is a disagreeable duty and I
found a way to obviate it by making a trapdoor device for his
kennel as shown in the sketch whereby he may lock himself in when
he crosses the threshold.

The outer half A of the hinged trapdoor is made heavier than the
inner half B by a cleat, C, and a strip, D, to cause the door to
swing shut. The tripper stick E is set between cleats C and F to
hold the door open. When the dog steps on the inner half of the
trapdoor B, it falls to stop G, releasing tripper stick E (which
is heavier on the top end H) to cause it to fall clear of the path
of the trapdoor. The door then swings shut in the direction of the
arrow, the latch I engaging a slot in the door as it closes, and
the dog has locked himself in for the night. The latch I is made
of an old-fashioned gate latch which is mortised in the bottom
joist of the kennel. When releasing the dog in the morning the
door is set for the evening.
--Contributed by Victor Labadie, Dallas, Texas.



** Polishing Cloths for Silver [32]

Mix 2 lb. of whiting and 1/2 oz. of oleic acid with 1 gal. of
gasoline. Stir and mix thoroughly. Soak pieces of gray outing
flannel of the desired size--15 by 12 in. is a good size--in this
compound. Wring the surplus fluid out and hang them up to dry,
being careful to keep them away from the fire or an open flame.
These cloths will speedily clean silver or plated ware and will
not soil the hands.

In cleaning silver, it is best to wash it first in hot water and
white soap and then use the polishing cloths. The cloths can be
used until they are worn to shreds. Do not wash them. Knives,
forks, spoons and other small pieces of silver will keep bright
and free from tarnish if they are slipped into cases made from the
gray outing flannel and treated with the compound.

Separate bags for such pieces as the teapot, coffee pot, hot-water
pot, cake basket and other large pieces of silverware will keep
them bright and shining.
--Contributed by Katharine D. Morse, Syracuse, N. Y.



** A Book-Holder [32]

Books having a flexible back are difficult to hold in an upright
position when copying from them. A makeshift combination of
paperweights and other books is often used, but with
unsatisfactory results.

[Illustration: Fig 2. Box Corner Makes a Book Holder]

The book-holder shown in the sketch will hold such books securely,
allow the pages to be turned easily and conceal the smallest
possible portion of each page.

The holder can be cut out of a box corner and fitted with two
screw eyes, which have the part shown by the dotted lines at A
(Fig. 1) removed. The length of the back board determines the
slope for the book rest.
--Contributed by James M. Kane, Doylestown, Pa.



** Clamping a Cork [33]

It is aggravating to continually break the cork of the stock
mucilage bottle because of its sticking to the neck of the bottle
after a supply has been poured out. If a stove bolt is inserted
lengthwise through the cork with a washer on each end and the nut
screwed up tightly, as shown in the sketch, the cork may be made
to last longer than the supply of mucilage and can be placed in a
new bottle and used over and over again.

[Illustration: Cork Clamp]



** Withdrawing Paper from under an Inverted Bottle [33]

Invert a bottle on a piece of paper near the edge of a table top
and ask anyone to remove the paper without overturning the bottle.
They will at once jerk the paper with the result that the bottle
will turn over. To remove the paper just strike the table top with
your right fist while pulling the paper slowly with your left
hand. As you strike the table the bottle will jump and release the
paper.
--Contributed by Maurice Baudier, New Orleans, La.



** Emergency Tire Repair [33]

A bone collar button makes a good substitute for a plug in
repairing a puncture in a single-tube bicycle tire.



** Broom Holder Made of a Hinge [33]

The broom holder shown in the sketch is made of an ordinary hinge
with one wing screwed to the wall. The loose wing has a large hole
drilled in it to receive the handle of the broom. The manner of
holding the broom is plainly shown in the sketch.
--Contributed by Theodore L. Fisher; Waverly, Ill.

[Illustration: Broom Holder]



** Making Proofs before the Negative Dries [33]

A correspondent of Camera Craft makes proofs from his developed,
but unfixed, negatives, by squeezing a sheet of wet bromide paper
into contact with the wet film and giving an exposure several
times longer than would be required under ordinary conditions,
using the paper dry. If the developer is well rinsed out of the
film, the exposure to artificial light necessary to make a print
will have no injurious effect upon the negative, which is, of
course, later fixed and washed as usual.



** Flower-Pot Stand [33]

A very useful stand for flower pots can be made of a piece of
board supported by four clothes hooks. The top may be of any size
suitable for the flower pot. The hooks which serve as legs are
fastened to the under side of the board in the same manner as
fastening the hook to a wall.
--Contributed by Oliver S. Sprout, Harrisburg, Pa.

[Illustration: Flower-pot Stand]



** A Line Harmonograph  [34]

[Illustration: Harmonograph]

As an apparatus capable of exciting interest, probably nothing so
easily constructed surpasses the harmonograph. Your attention will
be completely absorbed in the ever changing, graceful sweep of the
long pendulum, the gyrations of which are faithfully recorded in
the resulting harmonogram.

A careless impetus given to the pendulum may result in a very
beautiful harmonogram, but you may try innumerable times to
duplicate this chance record without success. No two hamonograms
are exactly alike. The harmonograph, while its pendulum swings in
accordance with well known natural laws, is exceedingly erratic
when it comes to obeying any preconceived calculations of its
operator. In this uncertainty lies the charm. If time hangs
heavily or a person is slightly nervous or uneasy, a harmonograph
is a good prescription.

The prime essential in a well working harmonograph is a properly
constructed universal joint. Where such a joint is made with
pivots for its bearings, one pair of pivots are very liable to
have more friction than the other, which retards the movement and
causes the harmonograph to undergo a continuous change of axis. To
obviate this difficulty, the joint should be made similar to those
used on scales. The general appearance of such a joint is shown in
the first illustration, Fig. 1. Stirrups A and B are made of 7/8
by 1/4-in. metal. Holes are drilled in each end of these stirrups
and filed out as shown at C. The two holes shown in the center of
the stirrup A are drilled to fasten the apparatus to the ceiling.
Two corresponding holes are drilled in B to fasten the long
pendulum F to the joint. The cross of the joint D has the ends
shaped as shown at E. The rounded shoulder on E is to prevent the
cross from becoming displaced by a jar or accident. The ends of
the cross are inserted through the holes C of the stirrups, then
slipped back so the knife edges engage in the V-shaped holes of
the stirrups. The cross must be so made that the knife edges will
be in the same plane. This can be determined by placing two of the
knife edges on the jaws of a vise and then laying two rules across
the other two edges. The rules should just touch the jaws of the
vise and the two knife edges of the cross. This makes a universal
joint almost free from friction and, what is most important,
prevents the pendulum from twisting on its own axis.

The pendulum F should be made of ash or oak, 1-3/4 by 2 in., with
a length depending on the height of the ceiling. A length of 7 ft.
is about right for a 10-ft. ceiling.

A small table or platform, K, as shown in the lower part of Fig.
1, is fastened to the lower end of the pendulum as a support for
the cards on which harmonograms are made. A weight, G, of about 30
or 40 lb.-a box filled with small weights will do--is attached to
the pendulum just above the table. Another weight of about 10 lb.
is attached as shown at H. A pedestal, J, provides a means of
support for the stylus. The stylus arm should have pin-point
bearings, to prevent any side motion.

The length of the short pendulum H, which can be regulated, as
shown in Fig. 1, should bear a certain and exactly fixed relation
to the length of the main pendulum, for the swinging times of
pendulums are inversely proportionate to their lengths, and unless
the shorter pendulum is, for instance, exactly one-third,
one-fourth, one-fifth, etc., as long as the other, that is, makes
respectively 3, 4 or 5 swings to one swing of the long pendulum,
they will not harmonize and a perfect harmonogram is not obtained.

A good stylus to contain the ink is easily made from a glass tube
1/4 in. in diameter. Heat the tube in an alcohol or Bunsen flame
and then, by drawing the two portions apart and twisting at the
same time, the tube may be drawn to a sharp point. An opening of
any desired size is made in the point by rubbing it on a
whetstone. Owing to the fact that the style of universal joint
described has so little friction, the stylus point must be very

[Illustration: Lines Made with the Harmonograph]

fine, or the lines will overlap and blur. A small weight, such as
a shoe buttoner, placed on the arm near the stylus will cause
enough friction to make the pendulum "die" faster and thus remedy
the trouble.
--Contributed by Wm. R. Ingham, Rosemont, Arizona.



** Cutting Circular Holes in Thin Sheet Metal [35]

In arts and crafts work, occasion often arises to cut a perfectly
circular hole in sheet copper or brass. To saw and file it out
takes time and skill. Holes up to 3 in. in diameter can be cut
quickly and accurately with an ordinary expansive bit.

Fasten the sheet metal to a block of wood with handscrews or a
vise. Punch a hole, with a nail set or punch, in the center of the
circle to be cut, large enough to receive the spur of the
expansive bit. A few turns of the brace will cut out the circle
and leave a smooth edge.
--Contributed by James T. Gaffney, Chicago.



** Key Card for Writing Unreadable Post Cards [35]

A key card for use in correspondence on postals that makes the
matter unreadable unless the recipient has a duplicate key card is
made as follows: Rule two cards the size of postal, one for the
sender and one for the receiver, dividing them into quarters.
These quarters are subsequently divided into any convenient number
of rectangular parts-six in this case.

These parts are numbered from one to six in each quarter beginning
at the outside corners and following in the same order in each
quarter. Cut out one rectangle of each number with a sharp knife,
distributing them over the whole card. Then put a prominent figure
1 at the top of one side, 2 at the bottom and 3 and 4 on the other
side. The numbering and the cutouts are

[Illustration: The Key Card]

shown in Fig. 1. The two key cards are made alike.

The key card is used by placing it over a postal with the figure 1
at the top and writing in the spaces from left to right as usual,
Fig. 3, then put 2 at the top, Fig. 4, and proceed as before, then
3 as in Fig. 5, and 4 as in Fig. 6. The result will be a jumble of
words as shown in Fig. 2, which cannot be read to make any sense
except by use of a key card.
--Contributed by W.J. Morey, Chicago.



** Homemade Carpenter's Vise [36]

The sketch shows an easily made, quick-working wood vise that has
proved very satisfactory. The usual screw is replaced by an open
bar held on one end by a wedge-shaped block,

[Illustration: Vise Made Entirely of Wood]

and the excess taken up on the other end by an eccentric lever.
The wedge is worked by a string passing through the top of the
bench and should be weighted on the other end to facilitate the
automatic downward movement.

The capacity of the vise, of course, depends on the size and shape
of the wedge-shaped block.
--Contributed by J.H. Cruger, Cape May City, N.J.



** Toning Blue on Bromide and Platinum [36]

After some experimenting to secure a blue tone on bromide prints,
a correspondent of the Photographic Times produced a very pleasing
bluish green tint by immersing the prints in a solution composed
of 30 gr. of ferricyanide of potash, 30 gr. citrate of iron and
ammonia, 1/2 oz. acetic acid and 4 oz. of water. After securing
the tint desired, remove the prints, rinse them in clean water for
a few minutes, and then place them in a dilute solution of
hydrochloric acid. Wash the prints thoroughly and hang them up
with clips to dry.



** Cutting Loaf Bread [36]

When cutting a loaf of bread do not slice it from the outer
crusted end. Cut through the center, then cut slices from the
center toward the ends. The two cut surfaces can be placed
together, thus excluding the air and keeping the bread fresh as
long as there is any left to slice.
--Contributed by L. Alberta Norrell, Augusta, Ga.



** How to Make an Electric Toaster [37]

The electric toaster shown in the sketch is not hard to make. The
framework comprising the base and the two uprights may be made
either of hardwood or asbestos board, says Popular Electricity. If
constructed of the former, the portion of the base under the coil,
and the inside surfaces of the two uprights should be covered with
a 1/8-in. sheet of well made asbestos paper, or thin asbestos
board may be substituted for this lining. Asbestos board is to be
preferred, and this material in almost any degree of hardness may
be purchased. It can be worked into shape and will hold wood
screws. The detail drawing gives all dimensions necessary to shape
the wood or asbestos board.

After preparing the base and uprights, drill 15 holes, 1/4 in.
deep, into the inside face of each upright to support the No. 6
gauge wires shown. The wires at the top and bottom for holding the
resistance wire are covered with asbestos paper and the holes for
these wires are 3/4 in. from the top and bottom, respectively, of
the uprights. The wires that form the cage about the heater coil
and are used for a support for the toast are 15 pieces of No. 6
gauge iron wire each 8 in. long. The screws that hold the uprights
in position should have the heads countersunk on the under side of
the base. The binding-posts should now be set in position and
their protecting covering

[Illustration: Detail of Toaster]

containing the reinforced cord left until the other parts are
finished.

To assemble, secure one upright in position using 1-1/2 in.
wood-screws. Place the other upright where it belongs without
fastening it and put the stretcher wires for holding the
resistance wire in place. Put the asbestos paper on these and with
the assistance of a helper begin winding on the heater coil.

[Illustration: Toaster Complete]

Use 80 ft. of 18-per-cent No. 22 gauge German-silver wire. Wind
the successive turns of wire so they will not touch each other and
fasten at each end with a turn or two of No. 16 gauge copper wire.
When this is complete have the helper hold the stretcher wires
while you tip the unfastened upright out and insert the wires of
the cage, then fasten the upright in place.

The wire from the binding-posts to the coil may be what is known
underwriters' wire or asbestos-covered wire No. 14 gauge, which is
held in place by double-headed tacks containing an insulation at
the head. These may be procured from electrical supply houses.
Connect the reinforced cord and terminals to the binding screws
and fasten the cover in place. This toaster will take four amperes
on 110-volt circuit.



** Cabinet for the Amateur's Workshop [37]

One of the most convenient adjuncts to an amateur's workbench is a
cabinet of some sort in which to keep nails, rivets, screws, etc.,
instead of leaving them scattered all about the bench. A very
easily made cabinet for this purpose is shown in the accompanying
illustration. The case may be made of 1/2-in. white pine or white
wood of a suitable size to hold the required number of drawers
which slide on strips of the same material, cut and dressed 1/2
in. square. The drawers are made of empty cigar boxes of uniform
size,

[Illustration: Empty Cigar Boxes Used for Drawers]

which, if one is not a smoker, may be readily obtained from any
cigar dealer, as they are usually thrown away when empty.

Small knobs may be added if desired, but these are not necessary,
as the spaces shown between the drawers give ample room to grasp
them with the fingers. Labels of some kind are needed, and one of
the neatest things for this purpose is the embossed aluminum
label, such as is stamped by the well known penny-in-the-slot
machines to be found in many railroad stations and amusement
places.
--Contributed by Frederick E. Ward, Ampere, N. Y.



** Uncurling Photographs [38]

Photograph prints can be kept from curling when dry, by giving
them the same treatment as was once used on films. Immerse for 5
minutes in a bath made by adding 14 oz. of glycerine to 16 oz. of
water,



** Soldering for the Amateur [38]

Successful soldering will present no serious difficulties to
anyone who will follow a few simple directions. Certain metals are
easier to join with solder than others and some cannot be soldered
at all. Copper, brass, zinc, tin, lead, galvanized iron, gold and
silver or any combination of these metals can be easily soldered,
while iron and aluminum are common metals that cannot be soldered.

It is necessary to possess a soldering copper, a piece of solder,
tinner's acid, sandpaper or steel wool, a small file and a piece
of sal ammoniac. If the soldering copper is an old one, or has
become corroded, it must be ground or filed to a point. Heat it
until hot (not red hot), melt a little solder on the sal ammoniac,
and rub the point of the copper on it, turning the copper over to
thoroughly tin the point on each face. This process is known as
tinning the iron and is very necessary to successful work.

After the copper is tinned you may place it in the fire again,
being careful about the heat, as too hot an iron will burn off the
tinning.

The parts to be soldered must be thoroughly cleaned by
sandpapering or the use of steel wool until the metal shows up
bright. Then apply the acid only to the parts to be soldered with
a small stiff brush or a small piece of cloth fastened to a stick,
or in a bent piece of tin to form a swab.

Tinner's acid is made by putting as much zinc in commercial
muriatic acid as will dissolve. This process is best accomplished
in an open earthenware dish. After the acid has ceased to boil and
becomes cool it may be poured into a wide-mouthed bottle which has
a good top or stopper, and labeled "Poison."

Place the parts to be soldered in their correct position and apply
the hot copper to the solder, then to the joint to be soldered,
following around with the copper and applying solder as is
necessary. In joining large pieces it is best to "stick" them
together in several places to hold the work before trying to get
all around them. A little practice will soon teach the requisite
amount of solder and the smoothness required for a good job.

In soldering galvanized iron, the pure muriatic acid should be
used, particularly so when the iron has once been used. --C. G.
S., Eureka Springs, Ark.



** Washboard Holder [39]

When using a washboard it will continually slip down in the tub.
This is considerable annoyance, especially if a large tub is used.
The washboard can be kept in place with small metal hooks, as
shown in the sketch. Two of these are fastened to the back of

[Illustration: Clip on the Washboard]

the washboard in the right place to keep it at the proper slant.
--Contributed by W. A. Jaquythe, Richmond, California.



** A Mission Bracket Shelf  [39]

The shelf consists of six pieces of wood A, B, C, D, E and F. The
material can be of any wood. I have one made of mahogany finished
in natural color, and one made of poplar finished black. The
dimensions given in the detail drawings are sufficient for anyone
to make this bracket. The amount of material required is very
small and can be made from scrap, or purchased from a mill
surfaced and sanded. The parts are put together with dowel pins.
--Contributed by A. Larson, Kenosha, Wis.

[Illustration: Details of the Wall Bracket]



** How to Make a Finger Ring [39]

While the wearing of copper rings for rheumatism may be a foolish
notion, yet there is a certain galvanic action

[Illustration: Tools for Forming the Ring]

set up by the contact of the acid in the system of the afflicted
person with the metal of the ring. Apart from this, however, a
ring may be made from any metal, such as copper, brass and silver,
if such metals are in plate or sheet form, by the following
method:

All the tools necessary are a die and punch which are simple to
make and will form a ring that will fit the average finger. Take a
3/4-in. nut, B, Fig. 1, and drill out the threads. This will leave
a clear hole, 7/8 in. in diameter, or a hole drilled the desired
size in a piece of iron plate will do as well. Countersink the top
of the hole so that the full diameter of the countersink will be
1-1/4 in. This completes the die. The punch A, is made of a piece
of 5/8 in. round iron, slightly rounded on the end so that it will
not cut through the metal disk. The dimensions shown in Fig. 1 can
be changed to suit the size of the finger to be fitted.

The metal used should be about 1/16 in. thick and 1-1/4 in. in
diameter. Anneal it properly by heating and plunging in water. Lay
it on the die so that it will fit nicely in the countersink and
drive it through the hole by striking the punch with a hammer.
Hold the punch as nearly central as possible when starting to
drive the metal through the hole. The disk will come out pan
shaped, C, and it is only necessary to remove the bottom of the
pan to have a band which will leave a hole 5/8 in. in diameter and
1-1/4 in. wide. Place the band, D, Fig. 2, on a stick so that the
edges can be filed and rounded to shape. Finish with fine emery
cloth and polish. Brass rings can be plated when finished.
--Contributed by H. W. Hankin, Troy, N. Y.



** How to Bind Magazines [40]

A great many readers of Popular Mechanics Magazine save their
copies and have them bound in book form and some keep them without
binding. The bound volumes make an attractive library and will
always be valuable works of reference along mechanical lines. I
bind my magazines at home evenings, with good results. Six issues
make a well proportioned book, which gives two bound volumes each
year.

The covers of the magazines are removed, the wire binders pulled
out with a pair of pliers and the advertising pages removed from
both sides, after which it will be found that the remainder is in
sections, each section containing four double leaves or sixteen
pages. These sections are each removed in turn from the others,
using a pocket knife to separate them if they stick, and each
section is placed as they were in the magazine upon each preceding
one until all six numbers have been prepared. If started with the
January or the July issue, the pages will be numbered
consecutively through the entire pages of the six issues.

The sections are then prepared for sewing. They are evened up on
the edges by jarring on a flat surface. They are then placed
between two pieces of board and all clamped in a vise. Five cuts,
1/8 in. deep, are made with a saw across the back of the sections,
as shown in Fig. 1. Heavy plain paper is used for the flyleaves.
The paper is cut double the same as the leaves comprising the
sections, making either one or two double sections for each side
as desired.

A frame for sewing will have to be made as shown in Fig. 2 before
the work can be continued on the book. The frame is easily made of
four pieces of wood. The bottom piece A should be a little larger
than the book. The two upright pieces B are nailed to the outside
edge, and a third piece, C, is nailed across the top. Small nails
are driven part way into the base C to correspond to the saw cuts
in the sections. A piece of soft fiber string is stretched from
each nail to the crosspiece C and tied.

Coarse white thread, size 16 or larger, is used for the sewing
material. Start with the front of the book. Be sure that all
sections are in their right places and that the flyleaves are
provided in the front and back. Take the sections of the flyleaves
on top, which should be notched the same as the saw cuts in the
book sections, and place them against the strings in the frame.
Place the left hand on the inside of the leaves where they are
folded and start a blunt needle, threaded double, through the
notch on the left side of the string No. 1 in Fig. 2. Take hold of
the needle with the right hand and pass it to the left around the
string No. 1, then back through the notch on the right side.
Fasten the thread by tying or making a knot in the end and passing
the needle through it. After drawing the thread tightly, pass the
needle through the notch on the left side of the string No. 2,
passing it around the string and tying in the same manner as for
No. 1. Each section is fastened to the five strings in the same
manner, the thread being carried across from each tie from No. 1
to 2 then to 3 and so on

[Illustration: Frame for Sewing Sections]

until all strings are tied. The string No. 5 is treated in the
same manner only that the needle is run through on the left side
of the string a second time, leaving the needle on the outside in
position for the next section, which is fastened the same as the
first, the needle being passed through the notch on the right side
of the string No. 5, and then to string No.4, passing around on
the right side and back on the left and so on. Keep the thread
drawn up tightly all the time.

After the sewing is completed cut the strings, allowing about 2
in. of the ends extending on each side. The fibers of these ends
are separated and combed out so that they can be glued to the
covers to serve as a hinge. A piece of cheesecloth is cut to the
size of the back and glued to it. Ordinary liquid glue is the best
adhesive to use.

Procure heavy cardboard for the covers and cut two pieces 1/2 in.
longer and just the same width as the magazine pages. The covering
can be of cloth, leather or paper according to the taste and
resources of the maker. The covering should be cut out 1 in.
larger on all edges than both covers and space on the back. Place
the cardboard covers on the book, allowing a margin of 1/4 in. on
all edges except the back, and measure the distance between the
back edges of the covers across the back of the book.

Place the cardboard covers on the back of the covering the proper
distance apart as measured for the back, and mark around each one.
Spread thin coat of glue on the surface of each and lay them on by
the marks made. Cut a notch out of the covering so it will fold
in, and, after gluing

[Illustration: The Bound Book]

a strip of paper to the covering between the covers to strengthen
the back, fold over the outside edges of the covering and glue it
down all around.

Place the cover on the book in the right position, glue the hinges
fast to the inside of the covers, then glue the first flyleaf to
the inside of the cover on both front and back and place the whole
under a weight until dry.
--Contributed by Clyde E. Divine, College View, Nebr.



** Metal Coverings for Leather Hinges [41]

A method of making a leather hinge work as well as an ordinary
steel butt is to cover the wings with sheet metal. The metal can
be fastened with nails or screws over the parts of the leather
attached to the wood. Tinplate, iron

[Illustration: Metal Parts Screwed on Leather Hinge]

hoops, zinc or thin brass cut in neat designs will make a leather
hinge appear as well as a metal hinge.
--Contributed by Tom Hutchinson, Encanto, Cal.



** Removing Plaster from Skin [41]

A hot-water bottle held against a porous plaster will assist in
quickly removing it from the skin.



** How to Make a Cheap Bracket Saw [42]

For the frame use 3/8-in. round iron, bending it as shown in the
diagram and filing a knob on each end, at opposite sides to each
other, on which to hook the blade. For the blade an old
talking-machine

[Illustration: Hacksaw Frame and Blade]

spring or a clock spring will do nicely. Heat the spring enough to
take some of the temper out of it, in order to drill the holes in
the ends, as shown, and file in the teeth. Make the blade 12 in.
long, with 10 teeth to the inch. A and B show how the blade fits
on the frame. -Contributed by Willard J. Hays, Summitville, Ohio.



** How to Make a Cannon [42]

A cannon like the one in the cut may be made from a piece of 1-in.
hydraulic pipe, A, with a steel sleeve, B, and a long thread plug,
C. Be sure to get hydraulic pipe, or double extra heavy, as it is
sometimes called, as common gas pipe is entirely too light for
this purpose. Don't have the pipe too long or the cannon will not
make as much

[Illustration: Toy Cannon]

noise. Seven or eight inches is about the right length for a 1-in.
bore. Screw the plug and pipe up tightly and then drill a 1/16-in.
fuse hole at D.

If desired the cannon may be mounted on a block of wood, F, by
means of a U-bolt or large staple, E.
--Contributed by Carson Birkhead, Moorhead, Miss.



** Controller for a Small Motor [42]

An easy way of making a controlling and reversing device for small
motors is as follows:

Cut a piece of wood (A) about 6 in. by 4-1/2 in., and 1/4 in.
thick, and another piece (B) 6 in. by 1 in., and 1/4 in. thick.
Drive a nail through this near the center for a pivot (C). To the
under side of one end nail a copper brush (D) to extend out about
an inch. On the upper side, at the same end, nail another brush
(E) so that it projects at both sides and is bent down to the
level of the end brush. Then on the board put

[Illustration: Reverse for Motor]

a semi-circle of brass-headed tacks as shown at F, leaving a small
space at the middle and placing five tacks on either side, so that
the end brush will come in contact with each one. Connect these
tacks on the under side of the board with coils of German-silver
wire, using about 8 in. of wire to each coil. Fix these by
soldering or bending over the ends of the tacks. Then nail two
strips of copper (G) in such position that the side brush will
remain on the one as long as the end brush remains on the tacks on
that side.

Put sides about 1-1/2 in. high around this apparatus, raising the
board a little from the bottom to allow room for the coil. A lid
may be added if desired. Connect up as shown.
--Contributed by Chas. H. Boyd, Philadelphia.



** How to Make a Simple Water Rheostat [43]

[Illustration: Wiring Plan for Water Rheostat]

The materials necessary are: One 5-point wood-base switch, 4 jars,
some sheet copper or brass for plates, about 5 ft. of
rubber-covered wire, and some No. 18 gauge wire for the wiring.

The size of the jars depends on the voltage. If you are going to
use a current of low tension, as from batteries, the jars need not
be very large, but if you intend to use the electric light current
of 110 voltage it will be necessary to use large jars or wooden
boxes made watertight, which will hold about 6 or 7 gal. Each jar
to be filled with 20 parts water to 1 part sulphuric acid. Jars
are set in a row in some convenient place out of the way.

Next cut out eight copper or brass disks, two for each jar. Their
size also depends on the voltage. The disks that are placed in the
lower part of the jars are connected with a rubber covered wire
extending a little above the top of the jar.

To wire the apparatus, refer to the sketch and you will see that
jar No. 1 is connected to point No. 1 on switch; No. 2, on No. 2,
and so on until all is complete and we have one remaining point on
switch. Above the jars place a wire to suspend the other or top
disks in the solution. This wire is also connected to one terminal
on the motor and to remaining point on switch. The arm of the
switch is connected to one terminal of battery, or source of
current, and the other terminal connected direct to remaining
terminal of motor.

Put arm of switch on point No. 1 and lower one of the top disks in
jar No. 1 and make contact with wire above jars. The current then
will flow through the motor. The speed for each point can be
determined by lowering top disks in jars. The top disk in jar No.
2 is lower down than in No. 1 and so on for No. 3 and No. 4. The
connection between point No. 5 on switch, direct to wire across
jars, gives full current and full speed.



** How to Build a Toboggan Sled [44]
By A. BOETTE

The first object of the builder of a sled should be to have a
"winner" both in speed and appearance. The accompanying
instructions for building a sled are designed to produce these
results.

The sled completed should be 15 ft. 2 in. long by 22 in. wide,
with the cushion about 15 in. above the ground. For the baseboard
select a pine board 15 ft. long, 11 in. wide and 2 in. thick, and
plane it on all edges. Fit up the baseboard with ten oak
foot-rests 22 in. long, 3 in. wide and 3/4 in. thick. Fasten them
on the under side of the baseboard at right angles to its length
and 16 in. apart, beginning at the rear. At the front 24 or 26 in.
will be left without cross bars for fitting on the auto front. On
the upper side of the cross bars at their ends on each side screw
a piece of oak 1 in. square by 14 ft. long. On the upper side of
the baseboard at its edge on each side screw an oak strip 3 in.
wide by 3/4 in. thick and the length of the sled from the back to
the auto front. These are to keep the cushion from falling out.
See Fig. 1. For the back of the sled use the upper part of a
child's high chair, taking out the spindles and resetting them in
the rear end of the baseboard. Cover up the outside of the
spindles with a piece of galvanized iron.

The construction of the runners is shown by Figs. 2 and 3. The
stock required for them is oak, two pieces 30 in. by 5 in. by
1-1/4 in., two pieces 34 in. by 5 in. by 1-1/4 in., two pieces 14
in. by 6 in. by 2 in., and four pieces 14 in. by 2 in. by 1 in.
They should be put together with large screws about 3 in. long.
Use no nails, as they are not substantial enough. In proportioning
them the points A, B and C, Fig. 2, are important. For the front
runners these measurements are: A, 30 in.; B, 4 in.; C, 15-1/2
in., and for the rear runners: A, 34 in.; B, 7 in. ; C, 16-1/2 in.
The screw eyes indicated must be placed in a straight line and the
holes for them carefully centered. A variation of 1/16 in. one way
or another would cause a great deal of trouble. For the steel
runners use 3/8 in. cold-rolled steel flattened at the ends for
screw holes. Use no screws on the running surface, however, as
they "snatch" the ice.

The mechanism of the front steering gear is shown at Fig. 3. A
3/4-in. steel rod makes a good steering rod. Flatten the steering
rod at one end and sink it into the wood. Hold it in place by
means of an iron plate drilled to receive the rod and screwed to
block X. An iron washer, Z, is used to reduce friction; bevel
block K to give a rocker motion. Equip block X with screw eyes,
making them clear those in the front runner, and bolt through. For
the rear runner put a block with screw eyes on the baseboard and
run a bolt through.

Construct the auto front (Fig. 4) of  3/4-in. oak boards. The
illustration shows how to shape it. Bevel it toward all sides and
keep the edges sharp, as sharp edges are best suited for the brass
trimmings which are to be added. When the auto front is in place
enamel the sled either a dark maroon or a creamy white. First
sandpaper all the wood, then apply a coat of thin enamel. Let
stand for three days and apply another coat. Three coats of enamel
and one of thin varnish will make a fine-looking sled. For the
brass trimmings use No. 27 B. & S. sheet brass 1 in. wide on all
the front edges and pieces 3 in. square on the cross bars to rest
the feet against. On the door of the auto front put the monogram
of the owner or owners of the sled, cutting it out of sheet brass.

For the steering-wheel procure an old freight-car "brake" wheel,
brass plated. Fasten a horn, such as used on automobiles, to the
wheel.

Make the cushion of leather and stuff it with hair. The best way
is to get some strong, cheap material, such as burlap, sew up one
end and make in

[Illustration: Construction a "Winner" Toboggan Sled]

the form of an oblong bag. Stuff this as tightly as possible with
hair. Then get some upholstery buttons, fasten a cord through the
loop, bring the cord through to the underside of the cushion, and
fasten the button by slipping a nail through the knot. Then put a
leather covering over the burlap, sewing it to the burlap on the
under side. Make the cushion for the back in the same way. On top
of the cushion supports run a brass tube to serve the double
purpose of holding the cushion down and affording something to
hold on to.

If desired, bicycle lamps may be fastened to the front end, to
improve the appearance, and it is well to have a light of some
kind at the back to avoid the danger of rear-end collisions.

The door of the auto front should be hinged and provided with a
lock so that skates, parcels, overshoes, lunch, etc. may be stowed
within. A silk pennant with a monogram adds to the appearance.

If desired, a brake may be added to the sled. This can be a
wrought-iron lever 1-1/2 in. by 1/2 in. by 30 in. long, so pivoted
that moving the handle will cause the end to scrape the ice. This
sled can be made without lamps and horn at a cost of about $15, or
with these for $25, and the pleasure derived from it well repays
the builder. If the expense is greater than one can afford, a
number of boys may share in the ownership.



** Burning Inscriptions on Trees

Scrape off the bark just enough to come to the first light under
coating, which is somewhat moist. With a lead pencil make an
outline of the inscription to be burnt on the tree and bring, the
rays of a large magnifying glass not quite to a fine focus on the
same. The tree will be burnt along the pencil marks, and if the
glass is not held in one spot too long, the inscription will be
burnt in as evenly as if it had been written.
--Contributed by Stewart H. Leland, Lexington, Ill.



** How to Make Small Gearwheels Without a Lathe [46]

To make small models sundry small gears and racks are required,
either cut for the place or by using the parts from an old clock.
With no other tools than a hacksaw, some files, a compass,

[Illustration: Making Model Wheels]

and with the exercise of a little patience and moderate skill,
very good teeth may be cut on blank wheels.

First take the case of a small gearwheel, say 1 in. outside
diameter and 1/16 in. thick, with twenty-four teeth. Draw a circle
on paper, the same diameter as the wheel. Divide the circumference
into the number of parts desired, by drawing diameters, Fig. 1.
The distance AB will be approximately the pitch. Now describe a
smaller circle for the base of the teeth and halfway between these
circles may be taken as the pitch circle.

Now describe a circle the same size as the largest circle on a
piece of 1/16-in. sheet metal, and having cut it out and filed it
up to this circle, fasten the marked-out paper circle accurately
over it with glue. Saw-cuts can now be made down the diameters to
the smaller circle with the aid of a saw guide, Fig. 2, made from
1/16-in. mild steel or iron. This guide should have a beveled
edge, E, from F to G, to lay along the line on which the saw-cut
is to be made. The straight-edge, CD, should be set back one-half
the thickness of the saw-blades, so that the center of the blade,
when flat against it, will be over the line FG. A small clearance
space, FC, must be made to allow the teeth of the saw to pass.

The guide should then be placed along one of the diameters and
held in position until gripped in the vise, Fig. 3. The first
tooth may now be cut, care being taken to keep the blade of the
saw flat up to the guiding edge. The Model Engineer, London, says
if this is done and the saw-guide well made, the cut will be
central on the line, and if the marking-out is correct the teeth
will be quite uniform all the way round. A small ward file will be
needed to finish off the teeth to their proper shape and
thickness.

In making a worm wheel the cuts must be taken in a sloping
direction, the slope and pitch depending on the slope and pitch of
the worm thread, which, though more difficult, may also be cut
with a hacksaw and file.

A bevel wheel should be cut in the same manner as the spur wheel,
but the cut should be deeper on the side which has the larger
diameter. To cut a rack the pitch should be marked along the side,
and the guide and saw used as before (Fig. 4).



** How to Make Four Pictures on One Plate [46]

Secure two extra slides for the plate holders and cut one corner
out on one

[Illustration: Four Photos on One Plate]

of them, as shown in Fig. 1. Make a hole in the other, as shown in
Fig. 2. With a lead pencil draw on the ground glass one line
vertical and one horizontal, each in the center. This will divide
the ground glass into four equal parts.

Focus the camera in the usual manner, but get the picture desired
to fill only one of the parts on the ground glass. Place the
plate-holder in position and draw the regular slide; substitute
one of the slides prepared and expose in the usual way.

If a small picture is to be made in the lower left-hand corner of
the plate, place the prepared slide with the corner cut, as shown
in Fig. 1. The slide may be turned over for the upper left hand
corner and then changed for slide shown in Fig. 2 for the upper
and lower right-hand corners.



** Electric Blue-Light Experiment  [47]

[Illustration: Electric Blue-light]

Take a jump-spark coil and connect it up with a battery and start
the vibrator. Then take one outlet wire, R, and connect to one
side of a 2-cp. electric lamp, and the other outlet wire, B, hold
in one hand, and press all fingers of the other hand on globe at
point A. A bright, blue light will come from the wires in the lamp
to the surface of the globe where the fingers touch. No shock will
be perceptible.



** Interesting Electrical Experiment  [47]

The materials necessary for performing this experiment are:
Telephone receiver, transmitter, some wire and some carbons,
either the pencils for arc lamps, or ones taken from old dry
batteries will do.

Run a line from the inside of the house to the inside of some
other building and fasten it to one terminal of the receiver. To
the other terminal fasten another piece of wire and ground it on
the water faucet in the house. If there is no faucet in the house,
ground it with a large piece of zinc.

Fasten the other end to one terminal of the transmitter and from
the other terminal of the same run a wire into the ground. The
ground here should consist either of a large piece of carbon, or
several pieces bound tightly together.

[Illustration: A Unique Battery]

If a person speak into the transmitter, one at the receiver can
hear what is said, even though there are no batteries in the
circuit. It is a well known fact that two telephone receivers
connected up in this way will transmit words between two persons,
for the voice vibrating the diaphragm causes an inductive current
to flow and the other receiver copies these vibrations. But in
this experiment, a transmitter which induces no current is used.
Do the carbon and the zinc and the moist earth form a battery?
--Contributed by Wm. J. Slattery, Emsworth, Pa.



** A Cheap Fire Alarm [47]

An electrical device for the barn that will give an alarm in case
of fire is shown in the accompanying diagram. A is a wooden block,
which is fastened under the loft at a gable end of the barn; B is
an iron weight attached to the string C, and this string passes up
through the barn to the roof, then over a hook or pulley and
across the barn, under the gable, and is fastened to the opposite
end of the barn.

D D are binding posts for electric wires. They have screw ends, as
shown, by which means they are fastened to the wooden block A.
They also hold the brass piece E and the strip of spring brass F
in place against the wooden block. G is a leather strap fastened
to the weight B and the spring F connected to the latter by a
small sink bolt.

[Illustration: Electric Fire Alarm]

At the house an electric bell is placed wherever convenient.
Several battery cells, of course, are also needed. Dry batteries
are most convenient. The battery cells and bell are connected in
the usual manner, and one wire from the bell and one from the
battery are strung to the barn and connected to the binding posts
D D.

If a fire occurs in the hay-mow the blaze will generally shoot
toward the gable soon after it starts, and will then burn the
string C, which allows the weight B to fall and pull the brass
spring against the iron piece E, which closes the circuit and
rings the bell in the house.

If desired, the string may be stretched back and forth under the
roof several times or drawn through any place that is in danger of
fire.
--Contributed by Geo. B. Wrenn, Ashland, Ohio.



** How to Make a Small Electric Furnace [48]

Take a block of wood and shape into a core. One like a loaf of
bread, and about that size, serves admirably. Wrap a layer of
asbestos around it and cover this with a thin layer of
plaster-of-paris. When the plaster is nearly dry wind a coil of
No. 36 wire around it, taking care that the wire does not touch
itself anywhere. Put another course of plaster-of-paris on this,
and again wind the wire around it. Continue the process of
alternate layers of plaster and wire until 500 ft. or more of the
latter has been used, leaving about 10 in. at each end for
terminals. Then set the whole core away to dry.

For a base use a pine board 10 in. by 12 in. by 1 in. Bore four
holes at one end for binding-posts, as indicated by E E. Connect
the holes in pairs by ordinary house fuse wire. At one side secure
two receptacles, B B, and one single post switch, C. Place another
switch at I and another binding-post at F. The oven is now ready
to be connected.

Withdraw the wooden core from the coils of wire and secure the
latter by bands of tin to the board. Connect the ends of the wire
to binding-posts E and F, as shown. From the other set of
binding-posts, E, run a No. 12 or No. 14 wire, connecting lamp
receptacles, B B, and switch, C, in parallel. Connect these three
to switch, D, in series with binding-post, F, the terminal of the
coil. Place 16-cp. lights in the receptacles and connect the fuses
with a 110-volt lighting circuit. The apparatus is now ready for
operation. Turn on switch, D, and the lamps, while C is open. The
coil will commence to become warm, soon drying out the
plaster-of-paris. To obtain more heat

[Illustration: Electric Furnace]

open one lamp, and to obtain still more open the other and close
switch C.
--Contributed by Eugene Tuttles, Jr., Newark, Ohio.



** How to Make an Ammeter [49]

Every amateur mechanic who performs electrical experiments will
find use for an ammeter, and for the benefit of those who wish to
construct such an instrument the following description is given:
The operative principle

[Illustration: Complete Ammeter and Details]

of this instrument is the same as that of a galvanometer, except
that its working position is not confined to the magnetic
meridian. This is accomplished by making the needle revolve in a
vertical instead of a horizontal plane. The only adjustment
necessary is that of leveling, which is accomplished by turning
the thumbscrew shown at A, Fig. 1, until the hand points to zero
on the scale.

First make a support, Fig. 2, by bending a piece of sheet brass to
the shape indicated and tapping for the screws CC. These should
have hollow ends, as shown, for the purpose of receiving the
pivoted axle which supports the hand. The core, Fig. 3, is made of
iron. It is 1 in. long, 1/4 in. wide and 1/8 in. thick. At a point
a little above the center, drill a hole as shown at H, and through
this hole drive a piece of knitting-needle about 1/2 in. long, or
long enough to reach between the two screws shown in Fig. 2. The
ends of this small axle should be ground pointed and should turn
easily in the cavities, as the sensitiveness of the instrument
depends on the ease with which this axle turns.

After assembling the core as shown in Fig. 4, it should be filed a
little at one end until it assumes the position indicated. The
pointer or hand, Fig. 5, is made of wire, aluminum being
preferable for this purpose, although copper or steel will do.
Make the wire 4-1/2 in. long and make a loop, D, 1/2 in. from the
lower end. Solder to the short end a piece of brass, E, of such
weight that it will exactly balance the weight of the hand. This
is slipped on the pivot, and the whole thing is again placed in
position in the support. If the pointer is correctly balanced it
should take the position shown in Fig. 1, but if it is not exactly
right a little filing will bring it near enough so that it may be
corrected by the adjusting-screw.

Next make a brass frame as shown in Fig. 6. This may be made of
wood, although brass is better, as the eddy currents set up in a
conductor surrounding a magnet tend to stop oscillation of the
magnet. (The core is magnetized when a current flows through the
instrument.) The brass frame is wound with magnet wire, the size
depending on the number of amperes to be measured. Mine is wound
with two layers of No. 14 wire, 10 turns to each layer, and is
about right for ordinary experimental purposes. The ends of the
wire are fastened to the binding posts B and C, Fig. 1.

A wooden box, D, is then made and provided with a glass front. A
piece of paper is pasted on a piece of wood, which is then
fastened in the box in such a position that the hand or pointer
will lie close to the paper scale. The box is 5-1/2 in. high, 4
in. wide and 1-3/4 in. deep, inside measurements. After everything
is assembled put a drop of solder on the loop at D, Fig. 5, to
prevent it turning on the axle.

To calibrate the instrument connect as shown in Fig. 7, where A is
the homemade ammeter; B, a standard ammeter; C, a variable
resistance, and D, a battery, consisting of three or more cells
connected in multiple. Throw in enough resistance to make the
standard instrument read 1 ohm [sic: ampere] and then put a mark
on the paper scale of the instrument to be calibrated. Continue in
this way with 2 amperes, 3 amperes, 4 amperes, etc., until the
scale is full. To make a voltmeter out of this instrument, wind
with plenty of No. 36 magnet wire instead of No. 14, or if it is
desired to make an instrument for measuring both volts and
amperes, use both windings and connect to two pairs of binding
posts.
--Contributed by J.E. Dussault, Montreal.



** How to Make a Three-Way Cock for Small Model-Work [50]

[Illustration: Three-way Valve]

In making models of machines it is often necessary to contrive
some method for a 3- or 4-way valve or cock. To make one, secure a
pet cock and drill and tap hole through, as shown in the cut. If
for 3-way, drill in only to the opening already through, but if
for a 4-way, drill through the entire case and valve. Be sure to
have valve B turned so as to drill at right angles to the opening
through it. After drilling, remove the valve, take off the burr
with a piece of emery paper and replace ready for work.



** Easy Experiments with Electric-Light Circuit [50]

An electric-light circuit will be found much less expensive than
batteries for performing electrical experiments. The sketch shows
how a small arc light and motor may be connected to the light
socket, A. The light is removed and a plug with wire connections
is put in its place. One wire runs to the switch, B, and the other
connects with the water rheostat, which is used for reducing the
current.

[Illustration: Arc-Light Motor and Water Rheostat]

A tin can, C is filled nearly to the top with salt water, and a
metal rod, D, is passed through a piece of wood fastened at the
top of the can. When the metal rod is lowered the current
increases, and as it is withdrawn the current grows weaker. In
this way the desired amount of current can be obtained.

By connecting the motor, E, and the arc light, F, as shown, either
one may be operated by turning switch B to the corresponding
point. The arc light is easily made by fastening two electric
light carbons in a wooden frame like that shown. To start the
light, turn the current on strong and bring the points of the
carbons together; then separate slightly by twisting the upper
carbon and at the same time drawing it through the hole.



** How to Make an Interrupter [51]

The Wenult interrupter is an instrument much used on large coils
and is far more efficient than the usual

[Illustration: Details of Interrupter]

form of vibrators. It can also be used with success on small coils
as well as large. Although it is a costly instrument to purchase,
it can be made with practically no expense and the construction is
very simple.

First procure a wide-mouthed bottle about 4 in. high, provided
with a rubber stopper. This stopper should be pierced, making two
holes about 1/4 in. in diameter. From a sheet of lead 1/16 in. in
thickness

[Illustration: The Completed Instrument]

cut a piece shaped like A, Fig. 1. Common tea lead folded several
times will serve the purpose. When in the bottle this lead should
be of such a size that it will only reach half way around, as
shown in B. To insert the lead plate, roll it up so it will pass
through the neck of the bottle, then smooth it out with a small
stick until it fits against the side, leaving the small strip at
the top projecting through the neck of the bottle. Bend this strip
to one side and fit in the stopper, as shown in C. A small
binding-post is fastened at the end of the strip.

Having fixed the lead plate in position, next get a piece of glass
tube having a bore of about 1/32 of an inch in diameter. A piece
of an old thermometer tube will serve this purpose. Insert this
tube in the hole in the stopper farthest from the lead plate. Get
a piece of wire that will fit the tube and about 6 in. long, and
fasten a small binding-post on one end and stick the other into
the tube. This wire should fit the hole in the tube so it can be
easily moved. In the hole nearest the lead plate insert a small
glass funnel.

The interrupter as it is when complete is shown at D, Fig. 1.
Having finished the interrupter, connect it with the
electric-light circuit as shown in Fig. 2. Fill the bottle with
water to about the line as shown in D, Fig. 1. Adjust the wire in
the small glass tube so that it projects about 1/8 in. Add
sulphuric acid until the water level rises about 1/16 in. Turn on
the current and press the button, B. If all adjustments are
correct, there will be a loud crackling noise from the
interrupter, a violet flame will appear at the end of the wire and
a hot spark will pass between the secondary terminals. If the
interrupter does not work at first, add more sulphuric acid
through the funnel and press the wire down a little more into the
liquid. A piece of wood, A, Fig. 2, should be inserted in vibrator
to prevent it from working.
--Contributed by Harold L. Jones, Carthage, N. Y.



** A Miniature "Pepper's Ghost" Illusion [52]

Probably many readers have seen a "Pepper's Ghost" illusion at
some amusement place. As there shown, the audience is generally
seated in a dark room at the end of which there is a stage with
black hangings. One of the audience is invited onto the stage,
where he is placed in an upright open

[Illustration: Pepper's Ghost]

coffin. A white shroud is thrown over his body, and his clothes
and flesh gradually fade away till nothing but his skeleton
remains, which immediately begins to dance a horrible rattling
jig. The skeleton then fades away and the man is restored again.

A simple explanation is given in the Model Engineer. Between the
audience and the coffin is a sheet of transparent glass, inclined
at an angle so as to reflect objects located behind the scenes,
but so clear as to be invisible to the audience and the man in the
coffin. At the beginning the stage is lighted only from behind the
glass. Hence the coffin and its occupant are seen through the
glass very plainly. The lights in front of the glass (behind the
scenes) are now raised very gradually as those behind the glass
are turned down, until it is dark there. The perfectly black
surface behind the glass now acts like the silver backing for a
mirror, and the object upon which the light is now turned--in this
case the skeleton--is reflected in the glass, appearing to the
audience as if really occupying the stage.

The model, which requires no special skill except that of
carpentry, is constructed as shown in the drawings.

The box containing the stage should be 14 in. by 7 in. by 7-1/2
in., inside dimensions. The box need not be made of particularly
good wood, as the entire interior, with the exception of the
glass, figures and lights, should be colored a dull black. This
can well be done by painting with a solution of lampblack in
turpentine. If everything is not black, especially the joints and
background near A, the illusion will be spoiled.

The glass should be the clearest possible, and must be thoroughly
cleansed. Its edges should nowhere be visible, and it should be
free from scratches and imperfections. The figure A should be a
doll about 4 in. high, dressed in brilliant, light-colored
garments. The skeleton is made of papier maché, and can be bought
at Japanese stores. It should preferably be one with arms
suspended by small spiral springs, giving a limp, loose-jointed
effect. The method of causing the skeleton to dance is shown in
the front view. The figure is hung from the neck by a blackened
stiff wire attached to the hammer wire of an electric bell, from
which the gong has been removed. When the bell works he will kick
against the rear wall, and wave his arms up and down, thus giving
as realistic a dance as anyone, could expect from a skeleton.

The lights, L and M, should be miniature electric lamps, which can
be run by three dry cells. They need to give a fairly strong
light, especially L, which should have a conical tin reflector to
increase its brilliancy and prevent its being reflected in the
glass.

Since the stage should be some distance from the audience, to aid
the illusion, the angle of the glass and the inclination of the
doll, A, has been so designed that if the stage is placed on a
mantle or other high shelf, the image of A will appear upright to
an observer sitting in a chair some distance away, within the
limits of an ordinary room. If it is desired to place the box
lower down, other angles for the image and glass may be found
necessary, but the proper tilt can be found readily by experiment.

The electric connections are so simple that they are not shown in
the drawings. All that is necessary is a two-point switch, by
which either L or M can be placed in circuit with the battery, and
a press button in circuit with the bell and its cell.

If a gradual transformation is desired, a double-pointed rheostat
could be used, so that as one light dims the other increases in
brilliancy, by the insertion and removal of resistance coils.

With a clear glass and a dark room this model has proved to be
fully as bewildering as its prototype.



** Experiment with Colored Electric Lamps [53]

To many the following experiment may be much more easily performed
than explained: Place the hand or other object in the light coming
from two incandescent lamps, one red and

[Illustration: Two-Colored Hand]

one white, placed about a foot apart, and allow the shadow to fall
on a white screen such as a table-cloth. Portions of the shadow
will then appear to be a bright green. A similar experiment
consists in first turning on the red light for about a minute and
then turning it off at the same time that the white one is turned
on. The entire screen will then appear to be a vivid green for
about one second, after which it assumes its normal color.



** To Explode Powder with Electricity [53]

A 1-in. hole was bored in the center of a 2-in. square block. Two
finishing nails were driven in, as shown in the sketch. These were
connected to terminals of an induction coil. After everything was
ready the powder was poured in the hole and a board weighted with
rocks placed over the block. When the button is pressed

[Illustration: Exploding Powder]

or the circuit closed in some other way the discharge occurs. The
distance between the nail points--which must be bright and
clean--should be just enough to give a good, fat spark.
--Contributed by Geo. W. Fry, San Jose, Cal.



** Simple Wireless System [54]

The illustrations will make plain a simple and inexpensive
apparatus for

[Illustration: Simple Wireless System]

wireless telegraphy by which I have had no difficulty in sending
messages across 1-1/2 miles of water surface. It is so simple that
the cuts scarcely need explanation. In Fig. 1 is seen the sending
apparatus, consisting of a 40-cell battery connected with two
copper plates 36 by 36 by 1/8 in. The plates are separated 6 in.
by a piece of hard rubber at each end.

In Fig. 2 are seen duplicates of these insulated plates, connected
with an ordinary telephone receiver. With this receiver I can hear
distinctly the electric signals made by closing and opening the
Morse key in Fig. 1, and I believe that in a short time I shall be
able to perfect this system so as to send wireless messages over
long distances.
--Contributed by Dudley H. Cohen, New York.



** Stop Crawling Water Colors [54]

To prevent water colors from crawling, add a few drops of ammonia
or lime water, or a solution of sal soda.



** Small Electrical Hydrogen Generator [54]

A small hydrogen generator may be made from a fruit jar, A (see
sketch), with two tubes, B and C, soldered in the top. The plates
E can be made of tin or galvanized iron, and should be separated
about 1/8 in. by small pieces of wood. One of these plates is
connected to metal top, and the wire from the other passes through
the tube B, which is filled with melted rosin or wax, to make it
airtight. This wire connects to one side of a battery of two
cells, the other wire being soldered to the metal top of the jar,
as shown. The jar is partly filled with a very dilute solution of
sulphuric acid, about 1 part of acid to 20 of water.

When the current of electricity passes between the plates E,
hydrogen gas is generated, which rises and passes through the
rubber hose D, into the receiver G. This is a wide-mouth bottle,
which is filled with water and inverted over a pan of water, F.

[Illustration: Hydrogen Generator]

The gas bubbling up displaces the water and fills the bottle.

If the receiver is removed when half full of gas, the remaining
space will be filled with air, which will mix with the gas and
form an explosive mixture. If a lighted match is then held near
the mouth of the bottle a sharp report will be heard.

If the bottle is fitted with a cork containing two wires nearly
touching, and the apparatus connected with an induction coil, in
such a manner that a spark will be produced inside the bottle, the
explosion will blowout the cork or possibly break the bottle.
Caution should be used to avoid being struck by pieces of flying
glass if this experiment is tried, and under no condition should a
lighted match or spark be brought near the end of the rubber hose
D, as the presence of a little air in the generator will make an
explosive mixture which would probably break the jar.



** Gasoline Burner for Model Work [55]

When making a small model traction engine or a locomotive the
question arises, "What shall the fuel be?" If you have decided to
use gasoline, then a suitable burner is necessary. A piece of
brass tubing about 3 in. in diameter and 6 in. long with caps
screwed on both ends and fitted with a filling plug and a bicycle
valve makes a good gasoline supply tank, says the Model Engineer,
London. The bicycle valve is used to give the tank an air pressure
which forces the gasoline to the burner.

The burner is made from a piece of brass tube, A, as is shown in
the illustration, 1/2 in. in diameter and 2-1/2 in. long, which is
plugged up at both ends, one end being drilled and reamed out to
5/16 in. Three rows of holes 1/16 in. in diameter are drilled in
the brass tube. One row is drilled to come directly on top, and
the other two at about 45 degrees from the vertical. It is then
fitted to a sheet steel base, B, by means of the clips, C C, Fig.
1. A piece of 1/8-in. copper pipe, P, is then coiled around the
brass tube, A, which forms the vaporizing coil. This coil should
have a diameter

[Illustration: Gasoline Burner]

of only 1 in. One end of the copper tube is bent around so it will
point directly into the reamed-out hole in the end of the brass
tube, A. A nipple, N, is made by drilling a 1/8-in. hole halfway
through a piece of brass and tapping to screw on the end of the
1/8-in. copper pipe. A 1/64-in. hole is then drilled through the
remaining part of the nipple. The other end of the copper tube is
connected to the supply tank. The distance between the nipple, N,
and the ends of the tube, A, should be only 5/16 of an inch. Fig.
2 shows the end view.



** A Homemade Telephone Receiver [55]

A telephone receiver that will do good work may be built very
cheaply as follows: For the case use an ordinary 1/2-lb.
baking-powder box with a piece of heavy wire soldered on the
inside, 1-5/16 in. from the bottom. For the magnet use a piece of
round hardened steel about 3/8 in. in diameter and 1-1/4 in. long.
If desired, a piece of an old round file may be used for the
magnet core, which should be magnetized previous to assembling,
either by passing a current of electricity around it, or by direct
contact with another magnet. The steel core should be wound with
about 250 ft. of No. 36 insulated wire, the ends of which should
be soldered to a piece of

[Illustration: Telephone Receiver]

lamp cord, passed through a hole in the bottom of the can and
knotted inside to prevent pulling out.

A disk of thin sheet-iron, such as is used by photographers for
tintypes (Ferrotype), should be cut to the diameter of the can,
taking care not to bend the iron. The magnet should then be placed
in the bottom of the can in an upright position and enough of a
melted mixture of beeswax and resin poured in to hold it in
position.

While the wax is still in a plastic condition the magnet should be
located centrally and adjusted so that the end will be 1/16 in. or
less below the level of the top of the copper ring.

After the wax has hardened the disk is slipped in and fastened
tightly by a ring of solder when the instrument is ready for use.



** How to Bind Magazines [56]

An easy way to bind Popular Mechanics in volumes of six months
each is to arrange the magazines in order and tie them securely
both ways with a strong cord. It is well to put two or three
sheets of tough white paper, cut to the size of the pages, at the
front and back for fly leaves.

Clamp the whole in a vise or clamp with two strips of wood even
with the back edges of the magazines. With a sharp saw cut a slit
in the magazines and wood strips about 1/2 in. deep and slanting
as shown at A and B, Fig. 1. Take two strips of stout cloth, about
8 or 10 in. long and as wide as the distance between the bottoms
of the sawed slits. Lay these over the back edge of the pack and
tie securely through the slits with a string thread--wrapping and
tying several times (C, Fig. 2).

If you have access to a printer's paper knife, trim both ends and
the front edge; this makes a much nicer book, but if the paper
knife cannot be used, clamp the whole between two boards and saw
off the edges, boards and all, smoothly, with a fine saw.

Cut four pieces of cardboard, 1/4 in. longer and 1/4 in. narrower
than the magazines after they have been trimmed. Lay one piece of
the board on the book and under the cloth strips. Use ordinary
flour paste and paste the strips to the cardboard and then rub
paste all over the top of the strips and the board. Rub paste over
one side of another piece of board and put it on top of the first
board and strips, pressing down firmly so that the strips are held
securely between the two boards. Turn the book over and do the
same with the other two boards.

After the paste has dried a few minutes take a piece of strong
cloth, duck or linen, fold and cut it 1 in. larger all around than
the book, leaving the folded edge uncut. Rub paste over one of the
board backs and lay one end of the cloth on it, smoothing and
creasing as shown at A, Fig. 3. Turn the book over and paste the
other side. The back edges should have a good coat of paste and a
strip of paper

[Illustration: Process of Homemade Binding]

the width of the thickness of the pack pasted on before pasting
the cloth to the second board back.

Cut off the corners and fold over the edges of the cloth, pasting
them down (Fig. 4). Rub paste on one side of a fly leaf and press
the back down on it. Turn the book over and paste a fly leaf to
the other back after the edges of the cloth have been folded down.
The backs must not be opened until the fly leaves are thoroughly
dry. Trim and tuck in the ends of the strip at the back edge.

When fixed this way your magazines make one of the most valuable
volumes you can possibly add to your library of mechanical books.
--Contributed by Joseph N. Parker, Bedford City, Va.



** A Homemade Acetylene-Gas Generator [57]

A simple acetylene-gas generator used by myself for several years
when

[Illustration: Acetylene Gas Generator]

out on camping trips was made of a galvanized iron tank, without a
head, 18 in. in diameter and 30 in. deep, B, as shown in the
sketch. Another tank, A, is made the same depth as B, but its
diameter is a little smaller, so that inverted it will just slip
easily into the tank B. In the bottom, or rather the top now, of
tank A is cut a hole, and a little can, D, is fitted in it and
soldered. On top and over can D is soldered a large tin can screw.
A rubber washer is fitted on this so that when the screw top, E,
is turned on it, the joint will be gas tight. Another can, C,
which will just slip inside the little can, is perforated with a
number of holes. This can C is filled about half full of broken
pieces of carbide and then placed in the little can D. A gas cock,
H, is soldered onto tank A, as shown, from which the gas may be
taken through a rubber tube. Fill tank B with water and set tank A
into it. This will cause some air to be enclosed, which can be
released by leaving the cock open until tank A settles down to the
point where the water will begin to run in the perforations of the
little tank. The water then comes in contact with the carbide and
forms gas, which expands and stops the lowering of tank A. Then
the cock must be closed and tubing attached. It is dangerous to
attempt to strike a match to light a jet or the end of the cock
while air is escaping and just as the first gas is being made.
Wait until the tank is well raised up before doing this.
--Contributed by James E. Noble, Toronto, Ont.



** Homemade Annunciator [57]

When one electric bell is operated from two push-buttons it is
impossible to tell which of the two push-buttons is being operated
unless an annunciator or similar device is used. A very simple
annunciator for indicating two numbers can be made from a small
box, Fig. 1, with an electric-bell magnet, A, fastened in the
bottom. The armature, B, is pivoted in the center by means of a
small piece of wire and has an indicator or hand, C, which moves
to either right or left, depending on which half of the magnet is
magnetized. If the back armature, D, of the magnet is removed the
moving armature will work better, as this will prevent the
magnetism from acting on both ends of the armature.

The wiring diagram, Fig. 2, shows how the connections are to be
made. If the pushbutton A is closed; the bell will ring and the
pointer will point at 1,

[Illustration: Annuciator and Wiring Diagram]

while the closing of the push-button B will ring the bell and move
the pointer to 2.
--Contributed by H. S. Bott, Beverly, N. J.



** How to Make a Box Kite [58]

As some of the readers of Amateur Mechanics may desire to build a
box kite, a simple method of constructing one of the modern type
is given in detail as follows: The sticks should be made of
straight grained wood, which may be either spruce, basswood or
white pine. The longitudinal corner spines, A A, should be 3/8 in.
square by 42 in. long, and the four diagonal struts, B, should be
1/4 in. by 1/2 in., and about 26 in. long. Two cloth bands should
be made to the exact dimensions given in the sketch and fastened
to the four longitudinal sticks with 1 oz. tacks. It is well to
mark the positions of the sticks on the cloth bands, either with a
soft lead-pencil or crayon, in order to have the four sides of
each band exactly equal. The ends of the bands should be lapped
over at least 1/2 in. and sewed double to give extra strength, and
the edges should be carefully hemmed, making the width, when
finished, exactly 12 in. Probably the best cloth for this purpose
is nainsook, although lonsdale cambric or lightweight percaline
will answer nearly as well.

The diagonal struts, B, should be cut a little too long, so that
they will be slightly bowed when put in position, thus holding the
cloth out taut and flat. They should be tied together at the
points of intersection and the ends should be wound with coarse
harness maker's thread, as shown at C, to prevent splitting. The
small guards, D, are nailed or glued to the longitudinal sticks to
prevent the struts slipping out of position. Of course the ends of
the struts could be fastened to the longitudinal strips if
desired, but if made as described the kite may be readily taken
apart and rolled up for convenience in carrying.

The bridle knots, E, are shown in detail at H and J. H is a square
knot, which may be easily loosened and

[Illustration: Detail of Box Kite]

shifted to a different position on the bridle, thus adjusting the
lengths of F and G. A bowline knot should be tied at J, as shown,
to prevent slipping. If the kite is used in a light wind, loosen
the square knot and shift nearer to G, thus shortening G and
lengthening F, and if a strong wind is blowing, shift toward F,
thereby lengthening G and making F shorter. In a very strong wind
do not use the bridle, but fasten a string securely to the stick
at K.
--Contributed by Edw. E. Harbert, Chicago.



** Lubricating a Camera Shutter [58]

An experienced photographer uses blacklead [graphite] for grooves
about a camera or holder. A small quantity is rubbed well into the
grooves and on the edges of shutters, that refuse to slide easily,
with gratifying results. Care must be taken to allow no dust to
settle in the holders, however.



** Simple Open-Circuit Telegraph Line [59]

By using the circuit shown in the sketch for short-distance
telegraph lines, the extra switches and wiring found in many
circuits are done away with. Closing either key will operate both
sounders, and, as the resistance of

[Illustration: Simple Telegraph Line]

the sounders is very high, the batteries do not run down for a
long time.
--Contributed by A. D. Stoddard, Clay Center, Kan.



** How to Make a Thermo Battery [59]

A thermo battery, for producing electricity direct from heat, can
be made of a wooden frame, A, with a number of nails, B, driven in
the vertical piece and connected in series with heavy copper
wires, C. The connections should all be soldered to give good
results, as the voltage is

[Illustration: Thermo Battery]

very low and the resistance of an unsoldered joint would stop the
current. The heat may be supplied by an alcohol lamp or other
device, and the current may then be detected by means, of a simple
galvanometer consisting of a square spool of No. 14 or No. 16
single-covered wire, E, with a pocket compass, F, placed on top.
Turn the spool in a north and south direction, or parallel with
the compass needle. Then, when the nail heads are heated and the
circuit completed, the needle will swing around it at right angles
to the coils of wire. Applying ice or cold water to the nail heads
will reverse the current.
--Contributed by A. C. A., Chicago.



** How to Discharge a Toy Cannon by Electricity [59]

A device for discharging a toy cannon by electricity can be easily
made by using three or four dry batteries, a switch and a small
induction coil

[Illustration: Electrical Attachment for Discharging Toy Cannon]

capable of giving a 1/8-in. spark. Fasten a piece of wood, A, to
the cannon, by means of machine screws or, if there are no
trunnions on the cannon, the wood may be made in the shape of a
ring and slipped on over the muzzle. The fuse hole of the cannon
is counterbored as shown and a small hole is drilled at one side
to receive a small piece of copper wire, E. The wood screw, C,
nearly touches E and is connected to one binding post of the
induction coil. The other binding post is connected with the wood
screw, D, which conducts the current into the cannon, and also
holds the pieces of wood, A and B, in position.

When the cannon is loaded, a small quantity of powder is placed in
the counterbore, and the spark between C and E ignites this and
discharges the cannon. A cannon may be fired from a distance in
this way, and as there is no danger of any spark remaining after
the current is shut off, it is safer than the ordinary cannon
which is fired by means of a fuse.
--Contributed by Henry Peck, Big Rapids, Mich.



** Simple Electric Lock [60]

The illustration shows an automatic lock operated by electricity,
requiring a strong magnet, but no weights or strings, which
greatly simplifies the device over many others of the kind.

[Illustration: Lock Operated by a Magnet]

The weight of the long arm, L, is just a trifle greater than the
combined weights of the short arms, A and S. The fulcrum of the
lever is at C, where there is a staple. The lever swings on one
arm of the staple and the other arm is so placed that when the
lever is in an upright position, with the long arm at L', it will
not fall because of its greater weight but stays in the position
shown. The purpose of this is to leave the short arm, A, when in
position at A', within the reach of the magnet. Arm L rests on an
L-shaped hook, H; in this position the door is locked.

To unlock the door, press the button, B. The momentum acquired
from the magnet by the short arms, A and S, is sufficient to move
the long arm up to the position of L'. To lock the door, press the
button and the momentum acquired from the magnet by the short
arms, now at A' and S', is sufficient to move the long arm down
from L' to the position at L.
--Contributed by Benjamin Kubelsky, Chicago.



** Direct-Connected Reverse for Small Motors [60]

A simple reverse for small motors can be attached directly to the
motor as shown in Fig. 1. Fig. 2 shows the construction of the
reverse block: A is a strip of walnut 5/8 in. square and 3/8 in.
thick with strips of brass or copper (BB) attached as shown. Holes
(CC) are drilled for the wire connections and they must be flush
with the surface of the block. A hole for a 1/2 in. screw is bored
in the block. In Fig. 1, D is a thin strip of walnut or other
dense, hard wood fitted to the binding posts of the brush holders,
to receive the screw in the center.

Before putting the reverse block on the motor, remove all the
connections between the lower binding posts and the brush holders
and connect both ends of the field coil to the lower posts. Bend
the strips BB (Fig. 2) to the proper position to make a wiping
contact with the nuts holding the strip of wood D, Fig. 1. Put the
screw in tight

[Illustration: Direct-Connected Reverse]

enough to make the block turn a little hard. Connect as shown in
the illustration. To reverse, turn the block so the strips change
connections and the motor will do the rest.
--Contributed by Joseph B. Keil, Marion, Ohio.



** A Handy Ice Chisel [61]

Fishing through the ice is great sport, but cutting the first
holes preparatory to setting the lines is not always an easy task.
The ice chisel here described will be found very handy, and may be
made at very slight expense.

In the top of an old ax-head drill a 9/16-in. hole, and then tap
it for a 3/8-in. gas-pipe, about 18 in. long. Thread the other end
of the pipe, and screw on

[Illustration: Combination Ax and Ice Chisel]

an old snow-shovel handle. When ready for use, screw the two
pieces together and you have your chisel complete.

A short ax-handle may be included in the outfit. When the holes
are finished and your lines set, unscrew the pipe from the head of
the ax, put in the handle, and your ax is ready to cut the wood to
keep your fire going.
--Contributed by C. J. Rand, West Somerville, Mass.



** More Uses for Pipe Fittings [61]

It would seem that the number of useful articles that can be made
from pipes and fittings is unlimited. The sketch shows two more
that may be added to the list. A and B are front and side views of
a lamp-screen, and C is a dumbbell. The lamp shade is particularly
useful for shading the eyes when reading or writing and, if
enameled white on the concave side, makes an excellent reflector
for drawing at night, or for microscopic work.

The standard and base, consisting of an ordinary pipe flange
bushed down to receive the upright nipple, are enameled a jet
black, and if the device is to be used on a polished table, a
piece of

[Illustration: Lamp Shade and Dumbbell]

felt should be glued to the bottom. A good way to hold the fan in
the nipple is to use a small wedge.

The dumbbells are made of short pieces of 3/4-in. pipe with
1-2-in. couplings fastened to each end by pouring melted lead in
the space between the pipes and the couplings. The appearance is
greatly improved by enameling black, and if desired the handles
may be covered with leather.
--Contributed by C. E. Warren, M. D., North Easton, Mass.



** Sealing-Wax Bent While Cold [61]

If a piece of sealing-wax is supported in a horizontal position by
one end, as shown at A in the sketch, it will gradually bend to
the shape indicated by the dotted lines B. To attempt bending it
with the hands would result in breaking it unless a steady
pressure were applied for a long time. This peculiar property is
also found in ice.

[Illustration: Bending Cold Sealing-Wax]



** Homemade Pottery Kiln [62]

A small kiln for baking clay figures may be built at a cost of $1.
The following shows the general plan of such a kiln which has
stood the test of 200 firings, and which is good for any work
requiring less than 1400° C.

Get an iron pail about 1 ft. high by 1 ft. across, with a cover.
Any old pail which is thick enough will do, while a new one will
cost about 80 cents. In the bottom of this cut a 2-in. round hole
and close it with a cork or wood plug, A, Fig. 1, which shall
project at least 2 in. inside the pail. Make a cylindrical core of
wood, B, Fig. 1, 8 in. long and 8 in. across. Make a

[Illustration: Homemade Pottery Kiln]

mixture of clay, 60%; sand, 15%; and graphite, 25%, kneading
thoroughly in water to a good molding consistency. Line the pail,
bottom and sides, with heavy paper and cover the core with same.
Now pack the bottom of the pail thoroughly with a 2-in. layer of
the clay mixture, and on it set the paper wrapped core, carefully
centering it. The 2 in. of space between the core and the sides of
the pail all around is to be filled with clay, C, as is shown in
the sketch, using a little at a time and packing it very tight. In
like manner make the cover of the kiln, cutting the hole a little
smaller, about 1 in. At the edge or rim of the cover encircle a
2-in. strip of sheet iron, E, Fig. 2, to hold the clay mixture, C.
Set aside for a few days until well dried.

While these are drying you may be making a muffle, if there is to
be any glazing done. This is a clay cylinder (Fig. 3) with false
top and bottom, in which the pottery to be glazed is protected
from any smoke or dust. It is placed inside the kiln, setting on
any convenient blocks which will place it midway. The walls of the
muffle should be about 1/2 in. thick, and the dimensions should
allow at least 1 in. of space all around for the passage of heat
between it and the walls of the kiln. By the time the clay of the
kiln is well dried, it will be found that it has all shrunk away
from the iron about 3/8 in. After removing all the paper, pack
this space-top, bottom and sides with moist ground asbestos. If
the cover of the pail has no rim, it may be fastened to the
asbestos and clay lining by punching a few holes, passing wire
nails through and clinching them. Fit all the parts together
snugly, take out the plugs in the top and bottom, and your kiln is
ready for business. The handle of the pail will be convenient for
moving it about, and it can be set on three bricks or some more
elaborate support, as dictated by fancy and expense.

The temperature required for baking earthenware is 1250
degrees--1310 degrees, C.,; hotel china, 1330 degrees; hard
porcelain, 1390 degrees-1410 degrees. These temperatures can not
be obtained in the above kiln by means of the ordinary Bunsen
burner. If will be necessary either to buy the largest size
Bunsen, or make one yourself, if you have the materials. If you
can get a cone which can be screwed into an inch pipe, file the
opening of the cone to 1/16 in. diameter, and jacket the whole
with a 2-1/2-in. pipe. The flame end of this burner tube should be
about 4-1/2 in. above the cone opening and should be covered with
gauze to prevent flame from snapping back. When lighted, the point
of the blue flame, which is the hottest part, should be just in
the hole in the bottom of the kiln. Such a burner will be cheaply
made and will furnish a kiln temperature of 1400 degrees, but it
will burn a great deal of gas.

A plumber's torch of medium size will cost more in the beginning,
but will be cheaper in operation. Whatever burner is used, the
firing should be gradual, and with especial caution the first
time. By experiment you will find that a higher temperature is
obtained by placing a 1-in. pipe 2-ft. long over the lid hole as a
chimney. It would be still more effective to get another iron
pail, 2 in. wider than the kiln, and get a down draft by inverting
it over the kiln at whatever height proves most suitable. --G. L.
W.



** How to Make a Small Medical Induction Coil [63]

The coil to be described is 3-1/2 in., full length of iron core,
and 3/4 in. in diameter.

Procure a bundle of small iron wire, say 1/4 in. in diameter, and
cut it 3-1/2 in. long; bind neatly with coarse thread and file the
ends smooth (Fig. 1). This done, make two wood ends, 1-1/4 by
1-1/4 in. and 3/8 in. thick, and varnish. Bore holes in the center
of each so the core will fit in snugly and leave about 1/4 in.
projecting from each end (Fig. 1).

After finishing the core, shellac two layers of  thick paper over
it between the ends; let this dry thoroughly. Wind two layers of
bell magnet wire over this, allowing several inches of free wire
to come through a hole in the end. Cover with paper and shellac as
before. Wind about 1/8 in. of fine wire, such

[Illustration: Medical Induction Coil]

as used on telephone generators, around the coil, leaving long
terminals. Soak the whole in melted paraffin and let cool; bind
tightly with black silk.

The vibrator is made of a piece of thin tin to which is soldered
the head of an iron screw and on the other side a small piece of
platinum, which can be taken from an old electric bell (Fig. 2).

Of course, a regulator must be had for the vibrator; this can be
accomplished by bending a stout piece of copper wire as shown. The
connections and the base for setting up are shown in the figures.
--Contributed by J. T. R., Washington, D. C.



** Mechanical Trick With Cards [63]

The following mechanical card trick is easy to prepare and simple
to perform:

First, procure a new deck, and divide it into two piles, one
containing the red cards and the other the black ones, all cards
facing the same way. Take the red cards, square them up and place
in a vise. Then, with a plane, plane off the upper right hand
corner and lower left hand corner, as in Fig. 1, about 1/16 in.

Then take the black cards, square them up, and plane off about
1/16 in. on the upper left hand corner and lower right hand
corner, as in Fig. 2.

Next restore all the cards to one pack, taking care to have the
first card red, the next black, and so on, every alternate card
being the same color. Bend the pack so as to give some spring to
the cards, and by holding one thumb on the upper left-hand corner

[Illustration: Card Trick]

all the cards will appear red to the audience; place thumb in the
center at top of pack and they will appear mixed, red and black;
with thumb on upper right-hand corner all cards appear black. You
can display either color called for.
--Contributed by Ralph Gingrich, Chicago.



** How to Make a Rain Gauge [64]

An accurate rain gauge may be easily constructed from galvanized
iron, as shown in the sketch herewith. The funnel, A, overlaps and
rests on the body, B, and discharges into the tube, C, the area of
which is one-tenth that of the top of the funnel. The depth of the
water in C is thus ten times the actual rainfall, so that by
measuring it with a stick marked off in tenths of an inch, we
obtain the result in hundredths of an inch.

A good size to make the rain gauge is as follows: A, 8 in.
diameter; C, 2.53 in. ; length of C, about 20 in. It should be
placed in an exposed location, so that no inaccuracy will occur
from wind currents. To find the fall of snow, pour a known
quantity

[Illustration: Rain Gauge]

of warm water on the snow contained in the funnel and deduct the
quantity poured in from the total amount in the tube.
--Contributed by Thurston Hendrickson, Long Branch, N.J.



** How to Make an Aquarium [64]

In making an aquarium, the first thing to decide on is the size.
It is well not to attempt building a very large one, as the
difficulties increase with the size. A good size is 12 by 12 by 20
in., and this is inexpensive to build.

First buy one length of 3/4 by 1/8-in. angle iron for the frame,
F, Fig. 1. This can be obtained at any steel shop and should cost
about 20 cents. All the horizontal pieces, B, should be beveled 45
degrees at the ends and drilled for 3/16 in. stove bolts. The
beveling may be done by roughing out with a hacksaw and finishing
with a file. After all the pieces are cut and beveled they should
be drilled at the ends for the 3/16-in. stove bolts, C. Drill all
the horizontal pieces, B, first and then mark the holes on the
upright pieces, A, through the holes already drilled, thus making
all the holes coincide. Mark the ends of each piece with a figure
or letter, so that when they are assembled, the same ends will
come together again. The upright pieces, A, should be countersunk
as shown in the detail, and then the frame is ready to assemble.

After the frame has been assembled take it to glazier and have a
bottom made of skylight glass, and sides and ends of double-thick
window glass. The bottom glass should be a good fit, but the sides
and ends should be made slightly shorter to allow the cement, E,
to form a dovetail joint as shown. When the glass is put in the
frame a space, D, will be found between the glass and the
horizontal pieces, B, of the frame. If this were allowed to remain
the pressure of the water would spring the glass and cause a leak
at E; so it is filled up with plaster of paris.

The cement, E, is made as follows: Take 1 gill of plaster of
paris, 1 gill of litharge, 1 gill of fine white sand, and 1/3 of a
gill of finely powdered rosin. Mix well and add boiled linseed oil
and turpentine until as thick as putty. Let

[Illustration: Detail of Aquarium Frame]

the cement dry three or four days before putting any water in the
aquarium.

In choosing stock for the aquarium it should be remembered that a
sufficient quantity of vegetable life is required to furnish
oxygen for the fish. In a well balanced aquarium the water
requires renewal only two or three times a year. It is well to
have an excess of plants and a number of snails, as the snails
will devour all the decaying vegetable matter which would
otherwise poison the water and kill the fish.

[Illustration: Aquarium Finished]

If desired, a centerpiece (A, Fig. 2) can be made of colored
stones held together by cement, and an inverted jar can be
supported in the position shown at B. If the mouth of the jar is
below the surface of the water it will stay filled and allow the
fish to swim up inside as shown. Some washed pebbles or gravel
should be placed on the bottom, and, if desired, a few Chinese
lilies or other plants may be placed on the centerpiece.



** Homemade Pneumatic Lock [65]

Mount an old bicycle hand-pump, A, on the door by means of a metal
plate, B, having a swinging connection at C. Fasten the lever, D,
to the door knob, and make a hinge connection with the pump by
means of a piece of sheet

[Illustration: Pneumatic Door-Opener]

brass, E, soldered to the end of the cylinder. All this apparatus
is on the inside of the door and is connected by a small rubber
tube, F, to a secret mouthpiece placed at some convenient
location. A small piece of spring brass, screwed to the door
frame, will open the door about 1/2 in. when the operator blows in
the mouthpiece, or if the door is within reach of the mouthpiece,
the operator may push the door at the same time that he blows,
thus doing away with the spring, which is only used to keep the
door from relocking.

One way of making the air connection with the outside is to bend
the tube F around and stick it through the keyhole. Few burglars
would ever think to blow in the keyhole.
--Contributed by Orton E. White, Buffalo, N. Y.



** A Homemade Water Motor [66]
By MRS. PAUL S. WINTER

In these days of modern improvements, most houses are equipped
with a washing machine, and the question that arises in the mind
of the householder is how to furnish the power to run it
economically. I referred this question to my husband, with the
result that he built a motor which proved so very satisfactory
that I prevailed upon him to give the readers of Amateur Mechanics
a description of it, hoping it may solve the same question for
them.

A motor of this type will develop about 1/2 hp. with a water
pressure of 70 lb. The power developed is correspondingly
increased or decreased as the pressure exceeds or falls below
this. In the latter case the power may be increased by using a
smaller pulley. Fig. 1 is the motor with one side removed, showing
the paddle-wheel in position; Fig. 2 is an end view; Fig. 3 shows
one of the paddles, and Fig. 4 shows the method of shaping the
paddles. To make the frame, several lengths of scantling 3 in.
wide by 1 in. thick (preferably of hard wood) are required. Cut
two of them 4 ft. long, to form the main supports of the frame,
AA, Fig. 1 ; another, 2 ft. 6 in. long, for the top, B, Fig. 1;
another, 26 in. long, to form the slanting part, C, Fig. 1; and
another, D, approximately 1 ft., according to the slant given C.
After nailing these together as shown in the illustration, nail
two short strips on each side of the outlet, as at E, to keep the
frame from spreading.

Cut two pieces 30 in. long. Lay these on the sides of the frame
with their center lines along the line FF, which is 15 in. from
the outside top of the frame. They are shown in Fig. 2 at GG. Do
not fasten these boards now, but mark their position on the frame.
Two short boards 1 in. wide

[Illustration: Detail of Homemade Waterwheel]

by 1 in. thick (HH, Fig. 2) and another 1 in. by 1-1/2 in. (I,
Fig. 2) form a substantial base.

Cut the wheel from sheet iron 1/16 in. thick, 24 in. in diameter.
This can be done roughly with hammer and chisel and then smoothed
up on an emery wheel, after which cut 24 radial slots 3/4 in. deep
on its circumference by means of a hacksaw. On each side of the
wheel at the center fasten a rectangular piece of 1/4-in. iron 3
by 4 in. and secure it to the wheel by means of four rivets; after
which drill a 5/8 in. hole through the exact center of the wheel.

Cut 24 pieces of 1/32-in. iron, 1-1/2 by 2-1/2 in. These are the
paddles. Shape them by placing one end over a section of 1-in.
pipe, and hammer bowl shaped with the peen of a hammer, as shown
in Fig. 4. Then cut them into the shape shown in Fig. 3 and bend
the tapered end in along the lines JJ, after which place them in
the slots of the wheel and bend the sides over to clamp the wheel.
Drill 1/8-in. holes through the wheel and sides of the paddles and
rivet paddles in place. Next secure a 5/8-in. steel shaft 12 in.
long to the wheel about 8 in. from one end by means of a key. This
is done by cutting a groove in the shaft and a corresponding
groove in the wheel and fitting in a piece of metal in order to
secure the wheel from turning independently of the shaft. Procure
two collars or round pieces of brass (KK, Fig. 2) with a 5/8-in.
hole through them, and fasten these to the shaft by means of set
screws to prevent it from moving lengthwise.

Make the nozzle by taking a piece of 1/2-in. galvanized pipe 3-1/2
in. long and filling it with babbitt metal; then drill a 3/16-in.
hole through its center. Make this hole conical, tapering from
3/16 in. to a full 1/2 in. This is best done by using a square
taper reamer. Then place the nozzle in the position shown in Fig.
1, which allows the stream of water to strike the buckets full in
the center when they reach the position farthest to the right.
Take the side pieces, GG, and drill a 1-in. hole through their
sides centrally, and a 1/4-in. hole from the tops to the 1-in.
holes. Fasten them in their proper position, with the wheel and
shaft in place, the shaft projecting through the holes just
mentioned. Now block the wheel; that is, fasten it by means of
wedges or blocks of wood until the shaft is exactly in the center
of the inch holes in the side pieces. Cut four disks of cardboard
to slip over the shaft and large enough to cover the inch holes.
Two of these are to be inside and two outside of the frames (one
to bear against each side of each crosspiece). Fasten these to the
crosspieces by means of tacks to hold them securely. Pour melted
babbitt metal into the 1/4-in. hole to form the bearings. When it
has cooled, remove the cardboard, take down the crosspieces, and
drill a 1/8-in. hole from the top of the crosspieces through the
babbitt for an oil-hole.

Secure sufficient sheet zinc to cover the sides of the frame. Cut
the zinc to the same shape as the frame and let it extend down to
the crosspieces EE. Tack one side on. (It is well to tack strips
of heavy cloth--burlap will do--along the edges under the zinc to
form a water-tight joint.) Fasten the crosspiece over the zinc in
its proper position. Drill a hole through the zinc, using the hole
in the crosspiece as a guide. Then put the wheel in a central
position in the frame, tack the other side piece of zinc in place
and put the other crosspiece in place. Place the two collars
mentioned before on the shaft, and fasten so as to bear against
the crosspieces, in order to prevent the wheel and shaft from
moving sidewise. If the bearings are now oiled, the shaft should
turn easily and smoothly. Fasten a pulley 4 or 6 in. in diameter
to the longest arm of the shaft.

Connect the nozzle to a water faucet by means of a piece of hose;
place the outlet over a drain, and belt the motor direct to the
washing-machine, sewing machine, ice-cream freezer, drill press,
dynamo or any other machinery requiring not more than 1/2 hp.

This motor has been in use in our house for two years in all of
the above ways, and has never once failed to give perfect
satisfaction. It is obvious that, had the wheel and paddles been
made of brass, it would be more durable, but as it would have cost
several times as much, it is a question whether it would be more
economical in the end. If sheet-iron is used, a coat of heavy
paint would prevent rust and therefore prolong the life of the
motor. The motor will soon pay for itself in the saving of laundry
bills. We used to spend $1 a month to have just my husband's
overalls done at the laundry, but now I put them in the machine,
start the motor, and leave them for an hour or so. At the end of
this time they are perfectly clean, and I have noticed that they
wear twice as long as when I sent them to the laundry.



** How to Make Silhouettes [68]

Photography in all branches is truly a most absorbing occupation.
Each of us who has a camera is constantly experimenting, and
everyone of us is delighted when something new is suggested for
such experiments.

[Illustration: Making a Silhouette with the Camera]

To use a camera in making silhouettes select a window facing north
if possible, or if used only at times when the sun is not on it,
any window will do, says the Photographic Times. Raise the window
shade half way, remove any white curtains there may be, and in the
center of the lower pane of glass paste by the four corners a
sheet of tissue paper that is perfectly smooth and quite thick, as
shown in the sketch at B. Darken the rest of the window, shutting
out all light from above and the sides. Place a chair so that
after being seated the head of the subject will come before the
center of the tissue paper, and as near to it as possible, and
when looking straight before him his face will be in clear profile
to the camera.

Draw the shades of all other windows in the room. Focus the camera
carefully, getting a sharp outline of the profile on the screen.
Do not stop down the lens, as this makes long exposure necessary,
and the subject may move. Correct exposure depends, of course, on
the lens, light and the plate. But remember that a black and white
negative is wanted with as little detail in the features as
possible. The best plate to use is a very slow one, or what is
called a process plate.

[Illustration: Sample Silhouette]

In developing get all possible density in the high lights, without
detail in the face, and without fog. Printing is best done on
contrasty development paper with developer not too strong.

The ideal silhouette print is a perfectly black profile on a white
ground. With a piece of black paper, any shape in stopping off
print may be made as shown at C in the sketch.



** How to Make a Galvanoscope [68]

A galvanoscope for detecting small currents of electricity can be
made from a coil of wire, A; a glass tube, B, full of water; a
core, C; and a base, D, with binding posts as shown. The core C,
which is made of iron and cork, is a trifle lighter than the water
it displaces and will therefore normally remain in the top of the
tube; but as soon as a current of electricity passes through the
coil, the core is drawn down out of sight. The current required is
very small, as the core is so nearly balanced that the least
attraction will cause it to sink.

The glass tube may be a test tube, as shown in Fig. 2, or an empty
developer tube. If one has neither a test tube nor developer tube,
an empty pill bottle may be used. The washers at the ends of the
coil can be made of fiber, hard rubber, or wood; or can be taken
from an old magnet. The base may be made of wood or any other
insulating material and should have four short legs on the bottom.
Make the coil of single-covered wire about No. 18 and connect ends
to binding posts as shown in Fig. 2.

The core is made by pushing a small nail through a piece of cork.
It should be made so that it will rise slowly when placed under
water. Some filing may be necessary to get the weight just right,
but it should be remembered that the buoyancy of the core can be
adjusted after the parts are assembled, by pressing the cork in
the bottom of the test tube. This causes compression in the water
so that some is forced into the upper cork, reducing its
displacement and causing it to sink. The lower cork is then slowly
withdrawn, by twisting, until the core slowly rises.

[Illustration: Galvanoscope]

The instrument will then be adjusted ready for use. Connect the
binding posts to a single cell of battery--any kind will do, as a
slight current will answer. On completing

[Illustration: Interior View]

the circuit the core will descend; or put in a switch or push
button on one of the battery wires. If the button be concealed
where the operator can reach it, the core will obey his command to
rise or fall, according to his control of the current. This is a
mysterious looking instrument, the core being moved without
visible connection to any other part.



** Lubricating Sheet Metal [69]

To lubricate sheet metal mix 1 qt. whale oil, 1 lb. white lead, 1
pt. water and 3 oz. finest graphite. Apply with a brush before the
metal enters the dies.



** An Optical Top [69]

One of the latest optical delusions, and one not easy to explain,
is Benham's color top. Cut out the black and white disk shown in
the figure, and paste on a piece of stiff cardboard. Trim the
edges of the cardboard to match the shape of the disk, and make a
pinhole in the center. Cut the pin in half and push it through
from the under side until the head of the pin touches the
cardboard. Spin slowly in a strong light and some of the lines
will appear colored. The colors appear different to different
people, and are changed by reversing the rotation.

[Illustration: An Optical Top]



** Card Trick with a Tapered Deck [70]

Another simple trick to perform but one not easily detected, is
executed by using a tapered deck of cards as shown in Fig. 1. A
cheap deck of cards is evened up square, fastened in a vise and
planed along the edge in such a manner that all the pack will be
tapered about 1/16 in. This taper is exaggerated in the
illustration which shows

[Illustration: Cards from a Tapered Deck]

one card that has been turned end for end.

It is evident that any card reversed in this way can be easily
separated from the other cards in the pack, which makes it
possible to perform the following trick: The performer spreads the
cards out, fan-like, and asks an observer to withdraw a card,
which is then replaced in any part of the pack. After thoroughly
shuffling the cards the performer then holds the deck in both
hands behind his back and pronouncing a few magic words, produces
the card selected in one hand and the rest of the pack in the
other. This is accomplished by simply turning the deck end for end
while the observer is looking at his card, thus bringing the wide
end of the selected card at the narrow end of the pack when it is
replaced. The hands are placed behind the pack for a double
purpose, as the feat then seems more marvelous and the observers
are not allowed to see how it is done.

In prize games, players having the same score are frequently
called upon to cut for low to determine which shall be the winner,
but a fairer way is to cut for high as a person familiar with the
trick shown in Fig. 2 can cut the cards at the ace, deuce, or
three spot, nearly every time, especially if the deck is a new
one. This is done by simply pressing on the top of the deck as
shown, before cutting, thus causing the increased ink surface of
the high cards to adhere to the adjacent ones. A little practice
will soon enable one to cut low nearly every time, but the cards
must be grasped lightly and the experiment should be performed
with a new deck to obtain successful results.
--Contributed by D.B.L., Chicago.



** A Constant-Pressure Hydrogen Generator [70]

By fitting three bottles, A, B, C, with rubber stoppers and
connecting with glass tubes as shown in the sketch, hydrogen or
other gases produced in a similar manner may be generated under
constant pressure. In making hydrogen, bottle B is partly filled
with zinc nodules formed by slowly pouring melted zinc into water.
Hydrochloric acid is then poured in the small funnel, thus partly
filling bottles A and C. When the acid rising from C comes in
contact with the zinc, hydrogen gas is generated and fills bottle
B. The gas continues to generate until the pressure is sufficient
to force the acid back down the tube into bottle C, when the
action ceases. As fast as the gas is used the acid rises in the
tube and generates more, thus keeping the pressure nearly
constant, the pressure depending on the difference between the
levels of the acid in bottle A and bottle B. As this device is
easily upset, a ring-stand should be used to prevent its being
broken, or if it is to be a permanent apparatus it may be mounted
on a substantial wooden base. This apparatus may also be used for
preparing acetylene gas or almost any gas which requires a mixture
of a solid and liquid in its preparation.
--Contributed by C. S. J., Detroit.



** Restoring Tone to a Cracked Bell [71]

Many a bell with a deadened tone due to a cracked rim, can be
given its original clear ringing sound by sawing out the crack
with a common hacksaw. Make the saw cut along the line of the
crack. The opening caused by the saw will allow the free vibration
of the metal.
--Contributed by F. W. Bently, Jr., Huron, S. Dak.



** How to Make a Paper Phonograph Horn [71]

Secure a piece of tubing about 1-3/4 in. long that will fit the
connection to the reproducer, and wrap a quantity of heavy thread
around one end as shown in the enlarged sketch A, Fig. 1. Form a
cone of heavy paper, 9 in. long and 3 in. in diameter, at the
larger end with the smaller end to fit the diameter of the tube A,
making it three-ply thick and gluing the layers together. Attach
this cone on the tube A where the thread has been wrapped with
glue, as shown in Fig. 2. Fig. 2 is also an enlarged sketch. Make
ten pieces about 1 ft. 10 in. in length and 3 in. wide from the
thin boards of a biscuit or cracker box. Cut an arc of a circle in
them on a radius of 2 ft. (Fig. 3). Make a 10-sided stick, 12 in.
long, that will fit loosely in the tube A, to which nail the 10
pieces as shown in Fig. 4, connecting the bottom by cross pieces,
using care to keep them at equal distances apart and in a circle
whose diameter is about 2 ft.

[Illustration: Detail of Phonograph Horn]

The cone is placed over the stick as shown by the dotted lines in
Fig. 4 and temporarily fastened in position. Cut out paper
sections (Fig. 5) that will cover each space between the 10
pieces, allowing 1 in. on one side and the top, in which to cut
slits that will form pieces to overlap the next section and to
attach with glue. Fasten the sections all around in like manner.
The next course is put on in strips overlapping as shown at B,
Fig. 6. Finish by putting on sections in the same way as the first
course, making it three-ply thick. Remove the form, trim to suit
and glue a piece of paper over the edge. When the glue is
thoroughly hardened, put on two coats of white and one of blue
paint, shading it to suit and striping it with gold bronze.



** How to Make a Hygrometer [71]

A homemade hygrometer, for determining the degree of moisture in
the atmosphere, is shown in the accompanying sketch and consists
of a board, A, with a nail at each end to hold the silk thread B.
A second piece of silk thread, C, is tied to the center of B and
connects with an indicating hand or pointer supported by the
bracket D. The axle on which the pointer revolves consists of a
piece of round wood, about the size of a lead-pencil, with a pin
driven in each end. A piece of tin, E, is cut V-shaped at each end
and bent up at the ends to form bearings for the pins. The silk
thread C is fastened to the wooden axle and is wrapped one or two
turns around it, so that when

[Illustration: The Hygrometer]

the thread is pulled the pointer will move on the scale. It will
be noticed that the thread B is not perfectly straight, but bends
toward D. For this reason a very small shrinkage of B, such as
occurs when the atmosphere is dry, will cause an increased
movement of C, which will be further increased in the movement of
the pointer. An instrument of this kind is very interesting and
costs nothing to make.
--Contributed by Reader, Denver.



** The Protection of a Spring Lock [72]

After shutting the front door and hearing the spring lock snap
into its socket, most people go off with a childlike faith in the
safety of their goods and chattels. But the cold fact is that
there is scarcely any locking device which affords less protection
than the ordinary spring lock. It is the simplest thing in the
world for a sneak thief to slip a thin knife between the
door-casing and the strip, push back the bolt, and walk in.

Fortunately, it is equally easy to block that trick. Take a narrow
piece of tin 3 or 4 in. long, bend it at right angles throughout
its length, and tack it firmly in the angle between the casing and
strip, so as to make it impossible to reach the bolt without
tearing off the strip.

Another way is to drive nails through the strip at intervals of
half an inch, enough to protect the bolt from being meddled with.



** A Controller and Reverse for a Battery Motor [72]

Secure a cigar or starch box and use to make the base, B. Two
wood-base switches, S S, are cut off a little past the center and
fastened to the base with a piece of wood between them. The upper
switch, S, is connected to different equal points on a coil of
wire, W, while the lower switch, S, is connected each point to a
battery, as shown. The reverse switch, R, is made from two brass
or copper strips fastened at the top to the base with screws and
joined together by a piece of hard rubber or wood with a small
handle attached. Connect wires A to the armature and wires F to
the field of the motor. By this arrangement one, two or three and
so on up until all the battery cells are used and different points
of resistance secured on the coil of wire. The reverse lever when
moved from right to left, or left to right, changes the direction
of the armature in the motor from one way to the other.
--Contributed by J. Fremont Hilscher, Jr., West St. Paul, Minn.

[Illustration: Motor Reverse and Controller]



** How to Build a Grape Arbor [73]

A grape arbor made of white pine, put together as shown in the
sketch, will last for several years. The 2 by

[Illustration: Grape-Arbor Trellis]

4-in. posts, A, are 7 ft. long. The feet, B, are made 2 by 4 in.,
4 ft. long, and rest on a brick placed under each end.



** How to Make a Toy Steam Engine [73]

A toy engine can be easily made from old implements which can be
found in nearly every house.

[Illustration: Toy Steam Engine Assembled]

The cylinder A, Fig. 1, is an old bicycle pump, cut in half. The
steam chest D, is part of the piston tube of the same pump, the
other parts being used for the bearing B, and the crank bearing C.
The flywheel Q can be any small-sized iron wheel; either an old
sewing-machine wheel, pulley wheel, or anything available. We used
a wheel from an old high chair for our engine. If the bore in the
wheel is too large for the shaft, it may be bushed with a piece of
hard wood. The shaft is made of heavy steel wire, the size of the
hole in the bearing B.

[Illustration: Valve Motion and Construction of Piston]

The base is made of wood, and has two wood blocks, H and K, 3/8
in. thick, to support bearing B, and valve crank S, which is made
of tin. The hose E connects to the boiler, which will be described
later. The clips FF are soldered to the cylinder and nailed to the
base, and the bearing B is fastened by staples.

The valve motion is shown in Figs. 2 and 3. In Fig. 2 the steam is
entering the cylinder, and in Fig. 3 the valve B has closed the
steam inlet and opened the exhaust, thus allowing the steam in the
cylinder to escape.

The piston is made of a stove bolt, E, Fig. 2, with two washers,
FF, and a cylindrical piece of hard wood, G. This is wound with
soft string, as shown in Fig. 3, and saturated with thick oil. A
slot is cut in the end of the bolt E, to receive the connecting
rod H. The valve B is made of an old bicycle spoke, C, with the
nut cut in half and filed down as shown, the space between the two
halves being filled with string and oiled.

The valve crank S, Fig. 1, is cut out of tin, or galvanized iron,
and is moved by a small crank on the shaft. This crank should be
at right angles to the main crank.

[Illustration: Engine in Operation]

The boiler, Fig. 4, can be an old oil can, powder can, or a syrup
can with a tube soldered to it, and is connected to the engine by
a piece of rubber tubing. The heat from a small gas stove will
furnish steam fast enough to run the engine at high speed. This
engine was built by W. G. Schuh and A. J. Eustice, of Cuba, Wis.



** Writing with Electricity [74]

Soak a piece of white paper in a solution of potassium iodide and
water for about a minute and then lay it on a piece of sheet
metal. Connect the sheet metal with the negative or zinc side of a
battery and then, using the positive wire as a pen, write your
name or other inscription on the wet paper.

[Illustration: Electrolytic Writing]

The result will be brown lines on a white background.
--Contributed by Geo. W. Fry, San Jose, Cal.



** To Photograph a Man in a Bottle [74]

Neither a huge bottle nor a dwarfed man is necessary for this
process, as it is merely a trick of photography, and a very
amusing trick, at that.

First, photograph the person to be enclosed in the bottle against
a dark plain background and mark the exact position on the ground
glass. Let the exposure be just long enough to show the figure
distinctly. Then place an empty bottle against a dark background
and focus so as to have the outlines of the bottle enclose those
of the man. Let this exposure be about twice the length of the
first, and the desired result is obtained.



** A Musical Windmill [74]

Make two wheels out of tin. They may be of any size, but wheel A
must be larger than wheel B. On wheel A fasten two pieces of wood,
C, to cross in the center, and place a bell on the four ends, as
shown. The smaller wheel, B, must be separated from the other with
a round piece of wood or an old spool. Tie four buttons with split
rings to the smaller wheel, B. The blades on the wheels should be
bent opposite on one wheel from the others so as to make the
wheels turn in different directions. When turning, the buttons
will strike the bells and make them ring constantly.

[Illustration: Musical Windmill]



** Optical Illusions [74]

By giving the page a revolving or rinsing motion the three
circular figures printed on the next page appear to rotate. The
best effect will be produced by laying the book down flat on the
desk or table and revolving, first

[Illustration: Move These Figures Rapidly with a Rinsing Motion]

in one direction and then in the opposite direction, in such a way
that any given point on the page will describe a circle of about
1/2 in. diameter. Fig. 1 then appears to rotate in the same
direction as the revolution; Fig. 2 appears to revolve in the
opposite direction, and Fig. 3 appears to revolve sometimes in the
same direction and at other times in the opposite direction.

A curious effect can be produced with Fig. 1 by covering up Figs.
2 and 3 with a piece of plain paper and laying a coin or other
small object on the paper. If the vision is then concentrated on
the coin or other object while same is being revolved, Fig. 1 will
be seen to rotate.



** Barrel-Stave Hammock  [75]

A hammock made of barrel staves is more comfortable than one would
think, considering the nature of the material employed in making
it. Good smooth staves should be selected for this purpose, and if
one cares to go to little trouble a thorough sandpapering will
make a great improvement. Cut half circles out of each stave, as
shown at AA, and pass ropes around

[Illustration: Cheap and Comfortable]

the ends as shown at B. When finished the weight will then be
supported by four ropes at each end, which allows the use of small
sized ropes, such as clothes lines. A hammock of this kind may be
left out in the rain without injury.
--Contributed by H.G.M., St. Louis, Mo.



** A Singing Telephone [75]

Those who have not already tried the experiment may be interested
to know that a telephone may be made to sing by holding the
receiver about 1/16 in. from the transmitter, as shown in the
illustration. The experiment will

[Illustration: To Make a Telephone Sing]

work well on most telephones, but not on all.

When the receiver is placed in the position shown it acts like an
ordinary buzzer, and the function of the transmitter will then be
that of an interrupter. The slightest movement of the transmitter
diaphragm will cause an increased movement of the receiver
diaphragm. This in turn will act on the transmitter, thus setting
up sympathetic vibrations between the two, which accounts for the
sound.



** A Microscope Without a Lens [76]
By E. W. DAVIS

Nearly everyone has heard of the pin-hole camera, but the fact
that the same principle can be used to make a microscope, having a
magnifying power of 8 diameters (64 times) will perhaps be new to
some readers. To make this lensless microscope, procure a wooden
spool, A (a short spool, say 1/2 or 3/4 in. long, produces a
higher magnifying power), and enlarge the bore a little at one
end. Then blacken the inside with india ink and allow to dry. From
a piece of thin

[Illustration: Detail of Lensless Microscope]

transparent celluloid or mica, cut out a small disk, B, and fasten
to the end having the enlarged bore, by means of brads. On the
other end glue a piece of thin black cardboard, C, and at the
center, D, make a small hole with the point of a fine needle. It
is very important that the hole D should be very small, otherwise
the image will be blurred.

To use this microscope, place a small object on the transparent
disk, which may be moistened to make the object adhere, and look
through the hole D. It is necessary to have a strong light to get
good results and, as in all microscopes of any power, the object
should be of a transparent nature.

The principle on which this instrument works is illustrated in
Fig. 2. The apparent diameter of an object is inversely
proportional to its distance from the eye, i. e., if the distance
is reduced to one-half, the diameter will appear twice as large;
if the distance is reduced to one-third, the diameter will appear
three times as large, and so on. As the nearest distance at which
the average person can see an object clearly is about 6 in., it
follows that the diameter of an object 3/4 in. from the eye would
appear 8 times the normal size. The object would then be magnified
8 diameters, or 64 times. (The area would appear 64 times as
large.) But an object 3/4-in. from the eye appears so blurred that
none of the details are discernible, and it is for this reason
that the pin-hole is employed.

Viewed through this microscope, a fly's wing appears as large as a
person's hand, held at arm's length, and has the general
appearance shown in Fig. 3. The mother of vinegar examined in the
same way is seen to be swarming with a mass of wriggling little
worms, and may possibly cause the observer to abstain from all
salads forever after. An innocent-looking drop of water, in which
hay has been soaking for several days, reveals hundreds of little
infusoria, darting across the field in every direction. These and
hundreds of other interesting objects may be observed in this
little instrument, which costs little or nothing to make.



** How to Make a Telegraph Key and Sounder [76]

The sounder, Fig. 1, is made from an old electric-bell magnet, D,
fastened to a wooden base. The lever, A, can be made of brass and
the armature, C, is made of iron. The pivot, E, is made from a
wire nail and is soldered to A. It should be filed to a point at
each end so as to move freely in the bearings, B, which are pieces
of hard wood. The spring, H, is fastened at each end by pins, bent
as shown, and should not be too strong or the magnet will be
unable to move the armature.

[Illustration: SOUNDER-A. brass: B. wood: C. soft iron; DD. coils
wound with No. 26 wire: E. nail soldered on A; FF. binding posts:
H spring]

The stop, K, is a wire nail driven deep enough in the base to
leave about 1/8 in. between the armature and the magnet. The
binding posts, F, may be taken from old dry batteries and are
connected to the two wires from the magnet by wires run in grooves
cut in the base.

The base of the key, Fig. 2, is also made of wood and has two
wooden bearings, E, which are made to receive a pivot, similar to
the one used in the sounder. The lever of the key is made of brass
and has a hardwood knob, A, fastened near the end. A switch, D,
connects with the pivot at F and can be either made from sheet
brass, or taken from a small one-point switch. The binding posts
are like those of the sounder, and are connected to the contacts,
K, by wires run in grooves cut in the wood.

[Illustration: KEY-A. wood; B. brass or iron soldered to nail; C.
brass; D. brass: E. wood: F. connection of D to nail; HH. binding
posts]



** How to Make a Music Cabinet [77]

A neat music cabinet can be made as shown in the accompanying
sketch. Each side, AA, Fig. 1, is cut from a board about 36 in. in
length and 16 in. wide. Both are alike and can be cut from the
same pattern. As the front legs curve out a little the main body
of the boards AA should be 15 in. wide. The back, B, should be
about 22 in. long by 16 in. wide and set in between sides AA. Cut
the top, C, 16 in. long and 14-1/2 in. wide. The bottom must be
the same length as the top and 13-1/2 in. wide.

The door, D, can be made panel as shown, or a single piece, 16 in.
wide and about 20 in. long. All material used is to be made from
boards that will dress to 3/4 in. thick.

[Illustration: How to Make a Music Cabinet]

Shelving may be put in as shown in Fig. 2 and made from 1/4-in.
material. Make 12 cleats, E, 13-1/2 in. long, from a strip of wood
1/2 by 3/4 in., with a groove 1/4 by 1/4 in. cut in them. Fasten 6
cleats evenly spaced on the inside of each of the sides, AA, with
3/4-in. brads. This will give seven spaces for music and as the
shelves are removable two places can be made into one.



** Easily Made Wireless Coherer [77]

A good wireless coherer may be made with very little expense, the
only materials necessary being a glass tube, two corks: a
magnetized needle and a quantity of iron and silver filings. Push
a piece of wire through one cork and place in the bottom of the
tube, as shown in the sketch.

Pour in the filings and insert the top cork with the needle pushed
through

[Illustration: Detail of Coherer]

from above. The point of the needle should barely touch the
filings and by slightly agitating the tube the iron filings will
separate from the silver and cling to the magnetized needle, as
shown.

In operation, the device must stand on end and should be connected
in the circuit as shown in the sketch. When the electrical waves
strike the needle, the conductivity of the filings is established
and a click is heard in the receiver.
--Contributed by Carl Formhals, Garfield, Ill.



** One-Wire Telegraph Line [78]

The accompanying wiring diagram shows a telegraph system that
requires no switches and may be operated with open-circuit
batteries on a one-wire

[Illustration: Diagram of One-Wire Line]

line with ground connections at each end. Any telegraph set in
which the key makes double contact can be connected up in this
way.
--Contributed by R. A. Brown, Fairport, N. Y.



** How to Make a Water Rheostat [78]

A water rheostat may be made by fitting a brass tube with a cork,
through which a piece of wire is passed. The brass tube may be an
old bicycle hand pump, A (see sketch), filled with water. Pushing
the wire, B, down into the water increases the surface in contact,
and thus decreases the resistance. An apparatus of this kind is
suitable for regulating the current from an induction coil, when
the coil is not provided with a regulator, and by using a piece of
pipe instead of the tube, it can be used to regulate the speed of
a motor.

When the pipe is used, a piece of brass or copper rod should be
substituted for the wire, in order to increase the surface. Adding
salt to the water will decrease the resistance, and, when used
with a motor, will give a greater speed.
--Contributed by John Koehler, Ridgewood, N. J.

[Illustration: Diagram of One-Wire Line Water Rheostat]



** Electric Door-Opener [78]

A very convenient and efficient device for unlocking any door
fitted with a spring lock is shown in the accompanying sketches. A
fairly stiff spring, A, is connected by a flexible wire cord to
the knob B. The cord is also fastened to a lever, C, which is
pivoted at D and is released by a magnetic trigger, E, made from
the armature and magnet of an old electric bell.

When the circuit is completed by means of a secret contact device
outside the door, the magnet, F, pulls down the armature, which
releases the trigger and allows the spring to open the lock. If
there are metal numbers on the outside of the door they may be
used for the secret contact, if desired,

[Illustration: Apparatus Placed on Inside of Door]

but if there are no numbers on the door, a small contact-board may
be constructed by driving about 12 brass headed tacks into a thin
piece of wood and making connections at the back as shown in the
wiring diagram.

In this particular diagram the tacks numbered 1 and 7 are used for
unlocking the door, the others being connected with the
electric-bell circuit as indicated, for the purpose of giving an
alarm should anybody try to experiment with the secret contacts.
By means of a pocket knife or other metal article the operator can
let himself in at any time by connecting the tacks numbered 1 and
7, while a person not knowing the combination would be liable to
sound the alarm. Of course, the builder of this device may choose
a combination of his own and may thus prevent anybody else from
entering the door, even those who read this description.
--Contributed by Perry A. Borden, Gachville, N. B.

[Illustration: Wiring Diagram]



** How to Tighten a Curtain-Roller Spring [79]

A common table fork can be used to hold the little projection on
the end of a curtain roller for tightening the spring. Hold the
fork firmly with one hand while turning the roller with the other.
Do not let go of the fork until the little catches are set in
position to prevent the spring from turning, or else the fork may
be thrown off with dangerous force.



** Alarm Clock Chicken Feeder [79]

An automatic poultry feeder, which will discharge the necessary
amount of corn or other feed at any desired time, may be made by
using an alarm clock as shown in the sketch. A small wire trigger
rests on the winding key and supports the swinging bottom of the
food hopper by means of a piece of string which connects the two.
When the alarm goes off the trigger drops and allows the door to
open, thus discharging the contents of the hopper.

After the device has been in operation for some time the hens will
run to the feeder whenever the. bell rings.
--Contributed by Dr. H. A. Dobson, Washington, D. C.

[Illustration: Will Open or Close Circuit as Desired]



** Homemade Disk-Record Cabinet [79]

Select some boards that have a nice grain and about 1 in. thick
and 12-in. wide. Cut the end pieces each 36-in. long and trim down
the edges so as to make them 11-3/8 in. wide. The top board is
made 28-in. long and full 12-in. wide. The three shelves are cut
25-in. long and the edges trimmed so they will be 11-3/8 in. wide.
The distance between the bottom of the top board and the top of
the first shelf should be 3 in. Two drawers are fitted in this
space, as shown in Fig. 1. A series of grooves are cut 1/4 in.
wide,

[Illustration: Cabinet Holding 32 Records]

1/4 in. deep and 3/4 in. apart on one side of the top and bottom
shelves, as shown in Fig. 2, and on both sides of the middle
shelf. The shelves should be spaced 9-5/8 in. for 10-in. records
and 5-5/8 in. for 6-in. records. A neat scroll design is cut from
a board 25 in. long to fill up and finish the space below the
bottom shelf.
--Contributed by H. E. Mangold, Compton, Cal.



** A Battery Rheostat [80]

In a board 7 in. long and 5 in. wide bore holes about 1/4 in.
apart, in a semicircle 2 in. from the bottom, and cut notches in
top end to correspond with the holes. From a piece of brass a
switch, C, is cut with a knob soldered on at the end. Nails for
stops are placed at DD. Two binding-posts are placed in board at A
and B. With about 9 ft. of fine iron wire attach one end to the
bottom of post A and run through first hole and over in first
notch to back of board and then through second hole and over
second notch and so on until E is reached, where the other end of
wire is fastened. Connect switch to post B.
--Contributed by Edmund Kuhn, Jr., East Orange, N. J.

[Illustration: Battery Rheostat]



** Automatic Time Switch [80]

This device may be used to either open or close the circuit at any
desired time. An alarm clock is firmly fastened to a wooden
bracket and provided with a small wood or metal drum, A, to which
is fastened a cord, B. The other end of the cord is tied to the
switch handle so that when the alarm goes off the switch is either
opened or closed, depending on whether the cord is passed over
pulley C or pulley D.

When the cord is passed over pulley C, as shown in Fig. 1, the
circuit will be closed when the alarm goes off, but if it is
passed over D the circuit will be opened. Pulley D is fastened to
a piece of spring steel, E, which in operation is bent, as shown
by the dotted lines, thus causing the switch to snap open quickly
and prevent forming an arc.
--Contributed by Douglas Royer, Roanoke, Va.

[Illustration: Will Open or Close Circuit as Desired]



** How to Make a Rotary Pump [81]

[Illustration: Details of Rotary Pump]

A simple rotary pump is constructed on the principle of creating a
vacuum in a rubber tube and so causing water to rise to fill the
vacuum. Figs. 3, 4 and 5 show all the parts needed, excepting the
crank and tubing. The dimensions and description given are for a
minimum pump, but a larger one could be built in proportion.

Through the center of a block of wood 4 in. square and 7/8 in.
thick (A, Figs. 1, 2 and 3) saw a circular opening 2-7/8 in. in
diameter. On each side of this block cut a larger circle 3-1/4 in.
in diameter, having the same center as the first circle (Fig. 3).
Cut the last circles only 1/4 in. deep, leaving the first circle
in the form of a ridge or track 3/8 in. wide, against which the
rubber tubing, E, is compressed by wheels. Bore two 1/4 in. holes
(HH, Fig. 1) from the outside of the block to the edge of the
inner circle. Put the rubber tube, E, through one of these holes,
pass it around the track and out through the other hole. Notice
the break (S) in the track; this is necessary in order to place in
position the piece holding the wheels.

Fig. 4 shows the wheel-holder, B. Make it of hard wood 3-1/8 in.
long, 1 in. wide and a little less than 7/8 in. thick, so that it
will run freely between the sides (Fig. 5) when they are placed.
Cut two grooves, one in each end, 1 in. deep and 1/2 in. wide. In
these grooves place wheels, CC, to turn on pins of stout wire.
These wheels should be 3/4 in. in diameter. When placed in the
holder their centers must be exactly 2 in. apart, or so arranged
that the distance between the edge of the wheels and the track (K,
Fig. 1) is equal to the thickness of the tubing when pressed flat.
If the wheels fit too tightly, they will bind; it too loose, they
will let the air through. Bore a hole through the middle of the
wheel-holder and insert the crankpin, D, which should be about 1/2
in. in diameter. The crankpin should fit tightly; if necessary
drive a brad through to keep it from slipping.

In the sides (Fig. 5) bore a hole in the center of the crankpin to
run in loosely. Now put all these parts together, as shown in the
illustration. Do not fasten the sides too securely until you have
tried the device and are sure it will run smoothly. For the crank
a bent piece of stout wire or a nail will serve, though a small
iron wheel is better, as it gives steadiness to the motion. In
this case a handle must be attached to the rim of the wheel to
serve as a crank. The drive wheel from a broken-down eggbeater
will do nicely. For ease in handling the pump, a platform should
be added.

To use the pump, fill the tube with water and place the lower end
of the tube in a reservoir of water. Make a nozzle of the end of a
clay pipe stem for the other end of the tube. Then turn the crank
from left to right. The first wheel presses the air out of the
tube, creating a vacuum which is immediately filled with water.
Before the first wheel releases the tube at the top, the other
wheel has reached the bottom, this time pressing along the water
that was brought up by the first wheel. If the motion of the
wheels is regular, the pump will give a steady stream. Two feet of
1/4-in. tubing, costing 10 cents, is all the expense necessary.
--Contributed by Dan H. Hubbard, Idana, Kan.



** How to Make a Fire Screen [82]

[Illustration: FIG.2  Made of Strap Iron]

A screen which will not interfere with the radiation of the heat
from the fire, and will keep skirts and children safe can be made
at little expense out of some strap iron. The screen which is
shown in Fig. 1, stands 20 in. high from the base to the top
crosspiece and is made of 3/4 by 1/4-in. and 1/2 by 1/4-in. iron.
The top and bottom pieces marked AA, Fig. 1, are 3/4 by 1/4 in.
and are 30 in. long, bent at an angle to fit the fireplace 7 in.
from each end, as shown in Fig. 2. The three legs marked BBB, Fig.
1, are of the same size iron and each leg will take 34 in. of
material. In shaping the feet of these three pieces give them a
slight tendency to lean toward the fire or inside of screen, says
a correspondent in the Blacksmith and Wheelwright. In the two
cross bars 1 in. from each end, A in Fig. 2, mark for hole and 3
in. from that mark the next hole. Take the center of the bar, B,
15 in. from each end, and mark for a hole, and 3-1/2 in. on each
side mark again and 3-1/2 in. beyond each of these two, mark
again.

Mark the legs 2-3/4 in. from the bottom and 2 in. from the top and
after making rivet-holes rivet them to the cross bars, AA, Fig. 1.

Cut six pieces, 17-1/2 in. long and punch holes to fit and rivet
onto the remaining holes in cross bars, AA, Fig. 1. Clean it up
and give it a coat of black Japan or dead black.



** Trap for Small Animals [82]

This is a box trap with glass sides and back, the panes of glass
being held in place by brads placed on both sides. The animal does
not fear to enter the box, because he can see through it: when he
enters, however, and touches the bait the lid is released and,
dropping, shuts him in. This is one of the easiest traps to build
and is usually successful.

[Illustration: Trap]



** Homemade Grenet Battery [83]

Procure an ordinary carbon-zinc, sal-ammoniac battery and remove
the zinc rod. If the battery has been used before, it is better to
soak the carbon cylinder for a few hours to remove any remaining
crystals of sal-ammoniac from its pores.

The truncated, conical zinc required is known as a fuller's zinc
and can be bought at any electrical supply dealer's, or, it may be
cast in a sand mold from scrap zinc or the worn-out zinc rods from
sal-ammoniac batteries. It should be cast on the end of a piece of
No. 14 copper wire. Amalgamation is not necessary for the zinc one
buys, but if one casts his own zinc, it is necessary to amalgamate
it or coat it with mercury. This may be done as follows:

Dip a piece of rag in a diluted solution of sulphuric acid (water
16 parts, acid 1 part); rub the zinc well, at the same time
allowing a few drops of mercury to fall on a spot attacked by the
acid. The mercury will adhere, and if the rubbing is continued so
as to spread the mercury, it will cover the entire surface of the
zinc, giving it a bright, silvery appearance.

Next procure what is known as a wire connector. This is a piece of
copper tube about 1-1/2 in. long having two thumb screws, one on
each end on opposite sides (Fig. 2). The upper screw is to connect
the battery wire, the lower one to raise and lower the zinc. The
battery is now complete, and the solution (Fig. 1) must be
prepared. Proceed as follows:

In 32 oz. of water dissolve 4 oz. potassium bichromate. When the
bichromate has all dissolved, add slowly, stirring constantly, 4
oz. sulphuric acid. Do not add the acid too quickly or the heat
generated may break the vessel containing the solution. Then pour
the solution into the battery jar, until it is within 3 in. of the
top. Thread the wire holding the zinc through the porcelain
insulator of the carbon cylinder and also through the wire
connector. Pull the zinc up as far as it will go and tighten the
lower thumb screw so that it holds the wire secure. Place the
carbon in the jar. If the solution touches the zinc, some of it
should be poured out. To determine whether or not the zinc is
touched by the solution, take out the carbon and lower the zinc.
If it is wet, there is too much liquid in the jar. The battery is
now ready for use.

To cause a flow of electricity, lower the zinc until it almost
touches the bottom of the jar and connect an electric bell or
other electrical apparatus by means of wires to the two binding
posts.

This battery when first set up gives a current of about two volts.
It is useful for running induction coils, or small electric
motors. When through using the battery, raise the zinc and tighten
the lower thumb screw. This prevents the zinc wasting away when no
current is being used.
--Contributed by H. C. Meyer, Philadelphia.

[Illustration: Fig.1 Details of Homemade Battery]



** Door-Opener for Furnace [83]

The accompanying diagram shows an arrangement to open the coal
door of a furnace. When approaching the furnace with a shovelful
of coal it is usually necessary to rest the shovel on the top of
the ash door, while the coal door is being opened. With my device
it is only necessary to press the foot pedal, which opens the
door. After putting in the coal, pressing the pedal closes the
door. The pulley in the ceiling must be placed a little in front
of the door, in order to throw the door open after lifting it from
the catch. A large gate hinge is used to hold the pedal to the
floor.
--Contributed by Edward Whitney, Madison, Wis.

[Illustration: Furnace Door Opener]



** How to Make an Efficient Wireless Telegraph [84]
By GEORGE W. RICHARDSON

A simple but very efficient wireless telegraph may be constructed
at slight cost from the following description:

The sending apparatus consists of nothing but an induction coil
with a telegraph key inserted in the primary circuit, i. e., the
battery circuit. This apparatus may be purchased from any
electrical-supply house. The price of the coil depends upon its
size, and upon the size depends the distance signals can be
transmitted. If, however, one wishes to construct his own coil he
can make and use, with slight changes, the jump-spark coil
described elsewhere in this book. This coil, being a 1-in. coil,
will transmit nicely up to a distance of one mile; while a 12-in.
coil made on the same plan will transmit 20 miles or even more
under favorable conditions.

Change the coil described, as follows: Insert an ordinary
telegraph key in the battery circuit, and attach two small pieces
of wire with a brass ball on each, by inserting them in the
binding-posts of the coil as shown at B B". Of these two terminal
wires one is grounded to earth, while the other wire is sent aloft
and is called the aerial line. This constitutes all there is to
the sending apparatus.

Now for the receiving apparatus. In the earlier receiving
instruments a coherer was used, consisting of a glass tube about
1/8-in. diameter, in which were two silver pistons separated by
nickel and silver filings, in a partial vacuum. This receiver was
difficult of adjustment and slow in transmission. An instrument
much less complicated and inexpensive and which will work well can
be made thus:

Take a 5-cp. incandescent lamp and break off the tip at the dotted
line, as shown in Fig. 5. This can be done by giving the glass tip
or point a quick blow with a file or other thin edged piece of
metal. Then with a blow-torch heat the broken edges until red hot
and turn the edges in as seen in Fig. 6. Remove the carbon
filament in the lamp and bend the two small platinum wires so they
will point at each other as in Fig. 6, W W. Screw the lamp into an
ordinary wall socket which will serve as a base as in Fig. 7. Make
a solution of 1 part sulphuric acid to 4 parts of water, and fill
the lamp about two-thirds full (Fig. 7). This will make an
excellent receiver. It will be necessary to adjust the platinum
points, W W, to suit the distance the message is to be worked. For
a mile or less the points should be about 1/16 in. apart, and
closer for longer distances.

The tuning coil is simply a variable choking coil, made of No. 14
insulated copper wire wound on an iron core, as shown in Fig. 7.
After winding, carefully scrape the insulation from one side of
the coil, in a straight line from top to bottom, the full length
of the coil, uncovering just enough to allow a

[Illustration: Aerial]

good contact for the sliding piece. The tuning is done by sliding
the contact piece, which is made of light copper wire, along the
convolutions of the tuning coil until you can hear the signals.
The signals are heard in a telephone receiver, which is shown
connected in shunt across the binding posts of the lamp holder
with one or two cells of dry battery in circuit, Fig. 7.

[Illustration: Details]

The aerial line, No.6 stranded, is run from binding-post B through
the choking or tuning coil, and for best results should extend up
50 ft. in the air. To work a 20-mile distance the line should be
100 or 150 ft. above the ground. A good way is to erect a wooden
pole on a house or barn and carry the aerial wire to the top and
out to the end of a gaff or arm.

To the end of the aerial wire fasten a bunch of endless loops made
of about No. 14 magnet wire (bare or insulated), attaching both
ends to the leading or aerial wire. The aerial wire should not
come nearer than 1 ft. at any point to any metal which is
grounded.

Run a wire from the other binding post, A, to the ground and be
sure to make a good ground connection.

For simple experimental work on distances of 100 ft. only, an
ordinary automobile spark coil can be used in place of the more
elaborate coil, Figs. 1 to 4.

The above-mentioned instruments have no patents on them, and
anyone is at liberty to build and use them. The writer does not
claim to be the originator, but simply illustrates the above to
show that, after all, wireless is very simple when it is once
understood. The fundamental principles are that induction travels
at right angles, 90 degrees, to the direction of the current. For
an illustration, if a person standing on a bridge should drop a
pebble into the water below, after contact he would note circles
radiating out over the surface of the water. These circles, being
at right angles, 90 degrees, to the direction of the force that
caused the circles, are analogous to the flow of induction, and
hence the aerial line, being vertical, transmits signals
horizontally over the earth's surface.



** Beeswax for Wood Filler [85]

When filling nail holes in yellow pine use beeswax instead of
putty, as it matches the color well.



** How to Make a Lathe [86]

A small speed-lathe, suitable for turning wood or small metal
articles, may be easily made at very little expense. A lathe of
this kind is shown in the cut (Fig. 1), where A is the headstock,
B the bed and C the tailstock. I run my lathe by power, using an
electric motor and countershaft, but it could be run by foot power
if desired. A large cone pulley would then be required, but this
may be made in the same manner as the small one, which will be
described later.

[Illustration: Assembled Lathe Bed and Bearing Details]

The bed of the machine is made of wood as shown in Figs. 2 and 3,
hardwood being preferable for this purpose. Fig. 2 shows an end
view of the assembled bed, and Fig. 3 shows how the ends are cut
out to receive the side pieces.

The headstock, Fig. 6, is fastened to the bed by means of carriage
bolts, A, which pass through a piece of wood, B, on the under side
of the bed. The shaft is made of 3/4-in. steel tubing about 1/8
in. thick, and runs in babbitt bearings, one of which is shown in
Fig. 5.

To make these bearings, cut a square hole in the wood as shown,
making half of the square in each half of the bearing. Separate
the two halves of the bearing slightly by placing a piece of
cardboard on each side, just touching the shaft. The edges which
touch the shaft should be notched like the teeth of a saw, so as
to allow the babbitt to run into the lower half of the bearing.
The notches for this purpose may be about 1/8 in. pitch and 1/8
in. deep. Place pieces of wood against the ends of the bearing as
shown at A and B, Fig. 4, and drill a hole in the top of the
bearing as shown in Fig. 4.

The bearing is then ready to be poured. Heat the babbitt well, but
not hot enough to burn it, and it is well to have the shaft hot,
too, so that the babbitt will not be chilled when it strikes the
shaft. If the shaft is thoroughly chalked or smoked the babbitt
will not stick to it. After pouring, remove the shaft and split
the bearing with a round, tapered wooden pin. If the bearing has
been properly made, it will split along the line of the notched
cardboard where the section of the metal is smallest. Then drill a
hole in the top as shown at A, Fig. 5, drilling just deep enough
to have the point of the drill appear at the lower side. This
cavity acts as an oil cup and prevents the bearing from running
dry.

The bolts B (Fig. 5) are passed through holes in the wood and
screwed into nuts C, which are let into holes

[Illustration: FIG. 6 Headstock Details]

D, the holes afterward being filled with melted lead.

This type of bearing will be found very satisfactory and may be
used to advantage on other machines. After the bearings are
completed the cone pulley can be placed on the shaft. To make this
pulley cut three circular pieces of wood to the dimensions given
in Fig. 6 and fasten these together with nails and glue. If not
perfectly true, they may be turned up after assembling, by rigging
up a temporary toolrest in front of the headstock.

The tail stock (Fig. 7) is fastened to the bed in the same manner
as the headstock, except that thumb nuts are used on the carriage
bolts, thus allowing the tail stock to be shifted when necessary.
The mechanism of the center holder is obtained by using a 1/2-in.

[Illustration: FIG.7 Details of Tailstock]

pipe, A, and a 1/2-in. lock nut, B, embedded in the wood. I found
that a wooden tool-rest was not satisfactory, so I had to buy one,
but they are inexpensive and much handier than homemade tool rest.
--Contributed by Donald Reeves, Oak Park, Ill.



** To Use Old Battery Zincs [87]

When the lower half of a battery zinc becomes eaten away the
remaining part can be used again by suspending it from a wire as
shown in the cut. Be sure and have a good connection at the zinc
binding post and cover that with melted paraffin. This prevents
corrosion, which would otherwise occur from the action of the sal
ammoniac or other chemical. The wire may be held at the top by
twisting it around a piece

[Illustration: Showing Zinc Suspended]

of wood or by driving a peg through the hole in the porcelain
insulator.
--Contributed by Louis Lauderbach, Newark, N.J.



** Callers' Approach Alarm [87]

This alarm rings so that callers approaching the door may be seen
before they ring the bell and one can exercise his pleasure about
admitting them.

If one has a wooden walk, the alarm is easy to fix up. Take up
about 5 ft. of the walk and nail it together so as to make a
trapdoor that will work easily. Place a small spring under one end
to hold it up about 1/4 in. (A, Fig. 2). Nail a strip of tin along
the under side of the trap near the spring and fasten another
strip on the baseboard, so that they will not touch, save when a
weight is on the trap. Connect up an electric bell, putting the
batteries and bell anywhere desired, and using rubber-covered

[Illustration: Alarm Rings When Caller Approaches]

wire outside the house, and the alarm is complete.

When a person approaching the house steps on the trap, the bell
will ring and those in the house can see who it is before the door
bell rings.
--Contributed by R. S. Jackson, Minneapolis, Minn.



** Easy Method of Electroplating [88]

Before proceeding to electroplate with copper, silver or other
metal, clean the articles thoroughly, as the least spot of grease
or dirt will prevent

[Illustration: Electroplating Apparatus]

the deposit from adhering. Then polish the articles and rub them
over with a cloth and fine pumice powder, to roughen the surface
slightly. Finally, to remove all traces of grease, dip the
articles to be plated in a boiling potash solution made by
dissolving 4 oz. American ash in 1-1/2 pt. of water. Do not touch
the work with the hands again. To avoid touching it, hang the
articles on the wires, by which they are to be suspended in the
plating bath, before dipping them in the potash solution; then
hold them by the wires under running water for ten minutes to
completely remove every trace of the potash.

For plating with copper prepare the following solution: 4 oz.
copper sulphate dissolved in 12 oz. water; add strong ammonia
solution until no more green crystals are precipitated. Then add
more ammonia and stir until the green crystals are re-dissolved
giving an intense blue solution. Add slowly a strong solution of
potassium cyanide until the blue color disappears, leaving a clear
solution; add potassium cyanide again, about one-fourth as much in
bulk as used in the decolorizing process. Then make the solution
up to 2 qt. with water. With an electric pressure of 3.5 to 4
volts, this will give an even deposit of copper on the article
being plated.

A solution for silver plating may be prepared as follows: Dissolve
3/4 oz. of commercial silver nitrate in 8 oz. of water, and slowly
add a strong solution of potassium cyanide until no more white
precipitate is thrown down. Then pour the liquid off and wash the
precipitate carefully. This is best done by filling the bottle
with water, shaking, allowing precipitate to settle and then
pouring off the water. Repeat six times. Having finished washing
the precipitate, slowly add to it a solution of potassium cyanide
until all the precipitate is dissolved. Then add an excess of
potassium cyanide--about as much as was used in dissolving the
precipitate--and make the solution up to 1 qt. with water. This
solution, with an electric pressure of 2 to 4 volts, will give a
good white coat of silver in twenty minutes to half-an-hour; use 2
volts for large articles, and 4 volts for very small ones. If more
solution is required, it is only necessary to double all given
quantities.

Before silver plating, such metals as iron, lead, pewter, zinc,
must be coated with copper in the alkaline copper bath described,
and then treated as copper. On brass, copper, German silver,
nickel and such metals, silver can be plated direct. The deposit
of silver will be dull and must be polished. The best method is to
use a revolving scratch brush; if one does not possess a buffing
machine, a hand scratch brush is good. Take quick, light strokes.
Polish the articles finally with ordinary plate powder.

The sketch shows how to suspend the articles in the plating-bath.
If accumulators are used, which is advised, be sure to connect the
positive (or red) terminal to the piece of silver hanging in the
bath, and the negative (or black) terminal to the article to be
plated. Where Bunsen cells are used, the carbon terminal takes the
place of the positive terminal of the accumulator. --Model
Engineer.



** An Ingenious Electric Lock for a Sliding Door [89]

The apparatus shown in Fig. 1 not only unlocks, but opens the
door, also, by simply pressing the key in the keyhole.

In rigging it to a sliding door, the materials required are: Three
flat pulleys, an old electric bell or buzzer, about 25 ft. of
clothesline rope and some No. 18 wire. The wooden catch, A (Fig.
1), must be about 1 in. thick

[Illustration: Electric Lock for Sliding Door]

and 8 in. long; B should be of the same wood, 10 in. long, with
the pivot 2 in. from the lower end. The wooden block C, which is
held by catch B, Can be made of a 2-in. piece of broomstick. Drill
a hole through the center of this block for the rope to pass
through, and fasten it to the rope with a little tire tape.

When all this is set up, as shown in Fig. 1, make a key and
keyhole. A 1/4 in. bolt or a large nail sharpened to a point, as
at F, Fig. 3, will serve for the key. To provide the keyhole, saw
a piece of wood, I, 1 in. thick by 3 in. square, and bore a hole
to fit the key in the center. Make a somewhat larger block (E,
Fig. 3) of thin wood with a 1/8-in. hole in its center. On one
side of this block tack a piece of tin (K, Fig. 3) directly over
the hole. Screw the two blocks together, being careful to bring
the holes opposite each other. Then, when the point of the key
touches the tin, and the larger part (F, Fig. 3) strikes the bent
wire L, a circuit is completed; the buzzer knocks catch A (Fig.
1), which rises at the opposite end and allows catch B to fly
forward and release the piece of broom-stick C. The weight D then
falls and jerks up the hook-lock M, which unlocks the door, and
the heavier weight N immediately opens it.

Thus, with a switch as in Fig. 3, the door can only be opened by
the person who has the key, for the circuit cannot be closed with
an ordinary nail or wire. B, Fig. 2, shows catch B, Fig. 1,
enlarged; 0, Fig. 2, is the cut through which the rope runs; H,
Fig. 1, is an elastic that snaps the catch back into place, and at
G the wires run outside to the keyhole.

This arrangement is very convenient when one is carrying something
in one hand and can only use the other. Closing the door winds up
the apparatus again.
--Contributed by E. H. Klipstein, 116 Prospect St., East Orange,
New Jersey.



** Parlor Magic for Winter Evenings [90]
By C. H. CLAUDY

You are seated in a parlor at night, with the lights turned low.
In front of you, between the parlor and the room back of it, is an
upright square of brightly burning lights, surrounding a perfectly
black space. The magician stands in front of this, in his shirt
sleeves, and after a few words of introduction proceeds to show
the wonders of his magic cave.

Showing you plainly that both hands are empty, he points with one
finger to the box, where immediately appears a small white china
bowl. Holding his empty hand over this bowl, some oranges and
apples drop from his empty hand into the bowl. He removes the bowl
from the black box, or cave, and hands its contents round to the
audience. Receiving the bowl again, he tosses it into the cave,
but it never reaches the floor--it disappears in midair.

The illusions he shows you are too many to retail at length.
Objects appear and disappear. Heavy metal objects, such as forks,
spoons and jackknives, which have been shown to the audience and
which can have no strings attached to them, fly about in the box
at the will of the operator. One thing changes to another and back
again, and black art reigns supreme.

Now all this "magic" is very simple and requires no more skill to
prepare or execute than any clever boy or girl of fourteen may
possess. It is based on the performance of the famous Hermann, and
relies on a principle of optics for its success. To prepare such a
magic cave, the requisites are a large soap box, a few simple
tools, some black paint, some black cloth, and plenty of candles.

The box must be altered first. One end is removed, and a slit,
one-third of the length from the remaining end, cut in one side.
This slit should be as long as the width of the box and about five
inches wide. On either side of the box, half way from open end to
closed end, should be cut a hole, just large enough to comfortably
admit a hand and arm.

Next, the box should be painted black both inside and out, and
finally lined inside with black cloth. This lining must be done
neatly-no folds must show and no heads of tacks. The interior must
be a dead black. The box is painted black first so that the cloth
used need not be very heavy; but if the cloth be sufficiently
thick, no painting inside is required. The whole inside is to be
cloth-lined, floor, top, sides and end.

[Illustration: Candle stand]

Next, the illumination in front must be arranged. If you can have
a plumber make you a square frame of gas-piping, with tiny holes
all along it for the gas to escape and be lit, and connect this by
means of a rubber tube to the gas in the house, so much the
better; but a plentiful supply of short candles will do just as
well, although a little more trouble. The candles must be close
together and arranged on little brackets around the whole front of
the "cave" (see small cut), and should have little pieces of
bright tin behind them, to throw the light toward the audience.
The whole function of these candles is to dazzle the eyes of the
spectators, heighten the illusion, and prevent them seeing very
far into the black box.

Finally, you must have an assistant, who must be provided with
either black gloves or black bags to go over his hands and arms,
and several black drop curtains, attached to sticks greater in
length than the width of the box, which are let down through the
slit in the top.

The audience room should have only low lights; the room where the
cave is should be dark, and if you can drape portieres between two
rooms around the box (which, of course, is on a table) so much the
better.

The whole secret of the trick lies in the fact that if light be
turned away from anything black, into the eyes of him who looks,
the much fainter light reflected from the black surface will not
affect the observer's eye. Consequently, if, when the exhibitor
puts his hand in the cave, his confederate behind inserts his
hand, covered with a black glove and holding a small bag of black
cloth, in which are oranges and apples, and pours them from the
bag into a dish, the audience sees the oranges and apples appear,
but does not see the black arm and bag against the black
background.

The dish appears by having been placed in position behind a black
curtain, which is snatched swiftly away at the proper moment by
the assistant. Any article thrown into the cave and caught by the
black hand and concealed by a black cloth seems to disappear. Any
object not too large can be made to "levitate" by the same means.
A picture of anyone present may be made to change into a grinning
skeleton by suddenly screening it with a dropped curtain, while
another curtain is swiftly removed from over a pasteboard
skeleton, which can be made to dance either by strings, or by the
black veiled hand holding on to it from behind, and the skeleton
can change to a white cat.

But illusions suggest themselves. There is no end to the effects
which can be had from this simple apparatus, and if the operators
are sufficiently well drilled the result is truly remarkable to
the uninitiated. The illusion, as presented by Hermann, was
identical with this, only he, of course, had a big stage, and
people clothed in black to creep about and do his bidding, while
here the power behind the throne is but a black-veiled hand and
arm. It can be made even more complicated by having two
assistants, one on each side of the box, and this is the reason
why it was advised that two holes be cut. This enables an
absolutely instantaneous change as one uncovers the object at the
moment the second assistant covers and removes the other.

[Illustration: The Magic Cave]

It is important that the assistants remain invisible throughout,
and if portieres are impossible, a screen must be used. But any
boy ingenious enough to follow these simple instructions will not
need to be told that the whole success of the exhibition depends
upon the absolute failure of the audience to understand that there
is more than one concerned in bringing about the curious effects
which are seen. The exhibitor should be a boy who can talk; a good
"patter"--as the magicians call it--is often of more value than a
whole host of mechanical effects and helpers. It is essential that
the exhibitor and his confederate be well drilled, so that the
latter can produce the proper effects at the proper cue from the
former. Finally, never give an exhibition with the "cave" until
you have watched the illusions from the front yourself; so that
you can determine whether everything connected with the draping is
right, or whether some stray bit of light reveals what you wish to
conceal.



** Reversing-Switch for Electrical Experiments [92]

A homemade reversing-switch, suitable for use by students of
electrical and engineering courses in performing experiments, is
shown in the diagram.

[Illustration: FIG.2  Suitable for Students' Use]

Referring to Fig. 1, A represents a pine board 4 in. by 4 in. and
a is a circular piece of wood about 1/4 in. square, with three
brass strips, b1, b2, b3, held down on it by two terminals, or
binding posts, c1, c2, and a common screw, d. Post c1 is connected
to d by means of an insulated wire, making them carry the same
kind of current (+ in the sketch).

About the center piece H moves a disk, held down by another disk F
(Fig. 2), which is fastened through the center piece to the wooden
base, A, by means of two wood screws. On the disk G are two brass
strips, e1 and e2, so arranged that, when handle K is turned to
one side, their one end just slips under the strips b1, b2, or b2,
b3, respectively, making contact with them, as shown in Fig. 2, at
L, while their other ends slide in two half-circular brass plates
f1, f2, held down on disk F by two other terminals, c3, c4, making
contact with them as shown at y, Fig. 2.

The action of the switch is shown in Fig. 1. Connect terminal c1
to the carbon of a battery, and c2 to the zinc. Then, if you turn
handle K to the right, so that the strips e1 and e2 touch b1 and
b2, respectively, terminal c3 will show +, and c1 -- electricity;
vice versa, if you turn the handle to the left so that e1 and e2
touch b2 and b3, respectively, terminal c3 will show - , and c4 +
electricity.

The switch is easy to make and of very neat appearance.



** How to Receive Wireless Telegraph Messages with a Telephone
[92]

Any telephone having carbon in the transmitter (all ordinary
telephones have carbon transmitters) can be used to receive
wireless messages by simply making a few changes in the
connections and providing a suitable antenna. Connect the
transmitter and receiver in series with three dry cells and run
one wire from the transmitter to the antenna. Connect the other
transmitter wire to a water or gas pipe in order to ground it, and
then hold the receiver to your ear. Any wireless telegraph message
within a radius of one mile will cause the transmitter to act as a
coherer, thus making the message audible in the receiver.

By using an ordinary telephone transmitter and receiver and a
1/2-in. jump spark coil, a complete wireless telegraph station may
be made, which will send or receive messages for a radius of one
mile. The accompanying wiring diagram shows how to make the
connections. By putting in an extra switch three of the sending
batteries may be switched in when receiving,

[Illustration: Wiring Diagram for Wireless Telegraph]

thus obviating the necessity of an extra set of batteries.
--Contributed by A. E. Joerin.



** Connecting Up Batteries to Give Any Voltage [93]

Referring to the illustration: A is a five-point switch (may be
homemade) ; B is a one-point switch, and C and C1 are binding
posts. When switch B is closed and A is on No. 1,

[Illustration: Battery Switch]

you have the current of one battery; when A is on No. 2 you
receive the current from two batteries; when on No. 3, from three
batteries; when on No. 4, from four batteries, and when on No. 5,
from five batteries. More batteries may be connected to each point
of switch B.

I have been using the same method for my water rheostat
(homemade). I have the jars of water where the batteries are and
the current coming in at a and b.
--Contributed by Eugene F. Tuttle, Jr., Newark, Ohio.



** A Simple Accelerometer [93]

[Illustration: Accelerometer]

A simple accelerometer for indicating the increase in speed of a
train was described by Mr. A. P. Trotter in a paper read before
the Junior Institution of Engineers of Great Britain. The device
consists of an ordinary 2-ft. rule, A, with a piece of thread tied
to the 22-in. mark, as shown in the sketch, and supporting the
small weight, B, which may be a button or other small object.

The device thus arranged, and placed on the windowsill of the car,
will indicate the acceleration and retardation as follows: Every
1/2 in. traveled by the thread, over the bent portion of the rule,
indicates an increase of or decrease of velocity to the extent of
1 ft. per second for each second. Thus, it the thread moved 2-1/4
in. in a direction opposite to the movement of the train, then the
train would be increasing its speed at the rate of 4-1/2 ft. per
second.

If the thread is tied at the 17-in. mark, then each half inch will
represent the mile per hour increase for each second. Thus if the
thread moves 1 in., it shows that the train is gaining 2 miles an
hour each second.



** An Egg-Shell Funnel [93]

Bottles having small necks are hard to fill without spilling the
liquid. A funnel cannot be used in a small opening, and pouring
with a graduate glass requires a steady hand. When you do not have
a graduate at hand, a half egg-shell with a small hole pricked in
the end will serve better than a funnel. Place the shell in an
oven to brown the surface slightly and it will be less brittle and
last much longer.
--Contributed by Maurice Baudier, New Orleans, La.



** Handy Electric Alarm [94]

An electric alarm which one may turn off from the bed without
arising combined with a light which may be turned on and off from
a lying position, so one can see the time, is the device of H. E.
Redmond, of Burlington, Wis. The alarm clock rests on a shelf, A,

[Illustration: Handy Electric Alarm]

which has a piece of metal, B, fastened in such a position that
the metal rod C, soldered to the alarm winder, will complete the
circuit and ring the bell. The two-point switch D is closed
normally at E, but may be closed at F any time desired, thus
turning on the small incandescent light G, which illuminates the
face of the clock. When the alarm goes off, the bell will continue
to ring until the switch is opened.



** To Keep Dogs and Cats Away from the Garbage-Can [94]

Last summer I was annoyed a great deal by dogs upsetting our
garbage can on the lawn, but finally executed a plan that rid the
yard of them in one afternoon.

I first secured a magneto out of an old telephone, then drove a
spike in a damp place under the porch, attached a wire to the
spike and ran the wire to one of the poles of the magneto. Then I
set the garbage-can on some blocks of wood, being careful not to
have it touch the ground at any point. I next ran a wire from the
other pole of the

[Illustration: Wiring]

magneto to the can, wrapping the wire around the can several
times. Then I sat down on the porch to wait.

It was not long before a big greyhound came along, putting his
forepaws on the top of the can to upset it. At the same instant I
gave the magneto a quick turn, which sent the dog away a very
surprised animal. This was repeated several times during the
afternoon with other dogs, and with the same result. --Contributed
by Gordon T. Lane, Crafton, Pa.



** How to Cross a Stream on a Log [94]

When crossing a water course on a fence rail or small log, do not
face up or down the stream and walk sideways, for a wetting is the
inevitable result. Instead, fix the eye on the opposite shore and
walk steadily forward. Then if a mishap comes, you will fall with
one leg and arm encircling the bridge. --C. C. S.



** Relay Made from Electric Bell [94]

It is not necessary to remove the adjusting-screw when changing an
electric bell into a relay. Simply twist it around as at A and
bend the circuit-breaking contact back as shown. It may be
necessary to remove the head of the screw, A, to prevent
short-circuiting with the armature.
--Contributed by A. L. Macey, New York City.

[Illustration: Relay]



** Foundry Work at Home [95]



** I The Equipment [95]

Many amateur mechanics who require small metal castings in their
work would like to make their own castings. This can easily be
done at home without going to any great expense, and the variety
and usefulness of the articles produced will make the equipment a
good investment.

With the easily made devices about to be described, the young
mechanic can make his own telegraph keys and sounders, battery
zincs, binding posts, engines, cannons, bearings, small machinery
parts, models and miniature objects, ornaments of various kinds,
and duplicates of all these, and many other interesting and useful
articles.

The first thing to make is a molding bench, as shown in Fig. 1. It
is possible to make molds without a bench, but it is a mistake to
try to do this, as the sand is sure to get on the floor, whence it
is soon tracked into the house. The bench will also make the
operation of molding much easier and will prove to be a great
convenience.

The bench should be made of lumber about 1 in. thick and should be
constructed in the form of a trough, as shown. Two cleats, AA,
should be nailed to the front and back to support the
cross-boards, BE, which in turn support the mold while it is being
made. The object of using the cleats and removable cross-boards
instead of a stationary shelf is to give access to the sand, C,
when it is being prepared.

About one or two cubic feet of fine molding-sand will be required,
which may, be purchased at the nearest foundry for a small sum.
Yellow sand will be found a little better for the amateur's work
than the black sand generally used in most foundries, but if no
yellow sand can be obtained the black kind will do. If there is no
foundry

[Illustration: Fig. 1 - Convenient Arrangement of Bench and Tools]

near at hand, try using sand from other sources, giving preference
to the finest sand and that which clings together in a cake when
compressed between the hands. Common lake or river sand is not
suitable for the purpose, as it is too coarse and will not make a
good mold.

For mixing and preparing the sand a small shovel, D, and a sieve,
E, will be required. If desired the sieve may be homemade.
Ordinary wire netting such as is used in screen doors, is about
the right mesh, and this, nailed to replace the bottom of a box,
makes a very good sieve.

The rammer, F, is made of wood, and is wedge-shaped at one end and
flat at the other, as shown. In foundries each molder generally
uses two rammers, but for the small work which will be described
one will be sufficient. An old teaspoon, G, will be found useful
in the molding operations and may be hung on the wall or other
convenient place when not in use.

The cloth bag, H, which can be made of a knitted stocking, is
filled with coal dust; which is used for a parting medium in
making the molds. Take a small lump of soft coal and reduce to
powder by pounding. Screen out all the coarse pieces and put the
remainder in the bag. A slight shake of the bag

[Illustration: Fig. 2; Homemade Flask]

over the mold will then cause a cloud of coal-dust to fall on it,
thus preventing the two layers of sand from sticking, but this
operation will be described more fully later on.

The flask, J, Fig. 1, is shown more clearly in Fig. 2. It is made
of wood and is in two halves, the "cope," or upper half, and the
"drag," or lower part. A good way to make the flask is to take a
box, say 12 in. by 8 in. by 6 in. high, and saw it in half
longitudinally, as shown. If the box is not very strong, the
corners should be braced with triangular wooden strips, A A, which
should be nailed in, previous to sawing. The wooden strips BB are
used to hold the sand, which would otherwise slide out of the
flask when the two halves of the mold are separated.

The dowels, CC, are a very important part of the flask as upon
them depends the matching of the two halves of the mold. A
wedge-shaped piece, CC, is nailed to each end of the cope, and the
lower pieces, DD, are then nailed on the drag so that they just
touch C when the flask is closed. The two halves of the flask will
then occupy exactly the same relative position whenever they are
put together.

After the flask is done make two boards as shown at K, Fig. 1, a
little larger than the outside of the flask. A couple of cleats
nailed to each board will make it easier to pick up the mold when
it is on the floor.

A cast-iron glue-pot makes a very good crucible for melting the
metal, which can be either aluminum, white metal, zinc or any
other metal having a low melting-point. This completes the
equipment with the exception of one or two simple devices which
will now be described.



** II - How to Make a Mold [96]

Having finished making the flask and other equipment, as
described, everything will be ready for the operation of molding.
It would be well for those who have never had any experience in
this line to visit a small brass foundry, where they can watch the
molders at work, as it is much easier to learn by observation; but
they must not expect to make a good mold at the first trial. The
first attempt usually results in the sand dropping out of the cope
when it is being lifted from the drag, either because of
insufficient ramming around the edges or because the sand is too
dry.

A good way to tell when the sand is moist enough is to squeeze it
in the hand. If it forms into a cake and shows all the
finger-marks, it has a sufficient amount of moisture, but if it
crumbles or fails to cake it is too dry. An ordinary watering-pot
will be found useful in moistening the sand, but care should be
taken not to get it too wet, or the hot metal coming in contact
with it when the mold is poured will cause such rapid evaporation
that the mold will "boil" and make a poor casting. A little
practice in this operation will soon enable the molder to
determine the correct amount of moisture.

When molding with sand for the first time it will be necessary to
screen it all before using it, in order to remove the lumps, and
if water is added, the sand should be thoroughly shoveled until
the moisture is evenly distributed. The sand is then ready for
molding.

The operation of making a mold is as follows: The lower half of
the flask, or "drag," and the pattern to be molded are both placed
on the cover board as shown at A. A quantity of sand sufficient to
completely cover the pattern is then sifted into the drag, which
is then filled level with the top with unscreened sand. This is
rammed down slightly with the rammer, and then more sand is added
until

[Illustration: Fig,. 3-Making a Mold]

it becomes heaped up as shown at B. It is then rammed again as
before.

It is impossible to describe just how hard a mold should be
rammed, but by observing the results the beginner can tell when a
mold is too hard or too soft, and thus judge for himself. If the
sand falls out of the flask when lifting the cope, or if it opens
up or spreads after it is poured, it shows that the mold has been
rammed too little, and if the surface of the sand next to the
pattern is cracked it shows that the mold has been rammed too
hard. It will be found that the edges of the mold can stand a
little more ramming than the middle. In finishing the ramming,
pound evenly all over the surface with the blunt end of the
rammer.

After ramming, scrape off the surplus sand with a straight-edged
stick, as shown at C, and scatter about 1/16 in. of loose sand
over the surface for a good bearing. Place another cover board on
top, as shown at D, and by grasping with both hands, as shown,
turn the drag other side up. Remove the upper cover board and
place the upper half of the flask, or "cope," in position, as
shown at E.

In order to prevent the two layers of sand sticking together, the
surface of the sand at E should be covered with coal-dust. This is
done by shaking the coal-dust bag over the flask, after which the
dust on the pattern may be removed by blowing. The cope is then
filled with sand and rammed in exactly the same manner as in the
case of the drag.

After the ramming is done a number of vent holes are made, as
shown at F, from the surface of the mold to the pattern, in order
to allow the escape of air and steam when the mold is being
poured. These vent holes may be made by pushing a wire about the
size of a knitting-needle down through the sand until it touches
the pattern. The "sprue," or pouring-hole, is next cut, by means
of the sprue-cutter shown at the right, which consists of a piece
of thin brass or steel tubing about 3/4 in. in diameter.

Now comes the critical part of the molding operation--that of
lifting the cope from the drag. It is here that the amateur often
becomes discouraged, as the sand is liable to fall out of the cope
and spoil the mold; but with a little practice and patience the
molder can lift the cope every time without breaking it, as shown
at G.

The next operation is that of cutting the gate, which carries the
molten metal from the sprue to the opening left by the pattern.
This is done with a spoon, a channel being cut about 3/4 in. wide
and about 1/4 in. deep. The pattern is then drawn from the mold,
as shown at H, by driving a sharp pointed steel rod into the
pattern and lifting it from the sand. When a metal pattern is used
a thread rod is used, which is screwed into a tapped hole in the
pattern. Before drawing it is well to tap the drawing-rod lightly
with another and larger rod, striking it in all directions and
thus loosening the sand slightly from the pattern. Some molders
tap the pattern gently when withdrawing, as shown at H, in order
to loosen any sand which has a tendency to stick.

After drawing the pattern, place the cope back on the drag, as
shown at J. Place a brick or other flat, heavy object on top of
the mold above the pattern, to prevent the pressure of the melted
metal separating the two halves of the mold, and then pour.



** III- Melting and Pouring [98]

Having prepared one or more molds, the next operation is that of
melting and pouring. An ordinary cast-iron glue-pot makes a good
crucible and can be easily handled by a pair of tongs, made out of
steel rod, as shown in the sketch. In order to hold the tongs
together a small link can be slipped on over the handle, thus
holding the crucible securely.

A second piece of steel rod bent in the form of a hook at the end
is very useful for supporting the weight of the crucible and
prevents spilling the molten metal should the tongs slip off the
crucible. The hook is also useful for removing the crucible from
the fire, which should be done soon after the metal is entirely
melted, in order to prevent overheating. The metal should be
poured into the mold in a small stream, to give the air a chance
to escape, and should not be poured directly into the center of
the opening, as the metal will then strike the bottom hard enough
to loosen the sand, thus making a dirty casting.

[Illustration: Fig. 4 -Pouring the Metal]

If, after being poured, the mold sputters and emits large volumes
of steam, it shows that the sand is too wet, and the castings in
such cases will probably be imperfect and full of holes.

A mold made in the manner previously described may be poured with
any desired metal, but a metal which is easily melted will give
the least trouble. One of the easiest metals to melt and one which
makes very attractive castings is pure tin. Tin melts at a
temperature slightly above the melting point of solder, and,
although somewhat expensive, the permanent brightness and
silver-like appearance of the castings is very desirable. A good
"white metal" may be made by mixing 75% tin, 15% lead, 5% zinc and
5% antimony. The object of adding antimony to an alloy is to
prevent shrinkage when cooling.

A very economical alloy is made by melting up all the old
type-metal, babbitt, battery zincs, white metal and other scrap
available, and adding a little antimony if the metal shrinks too
much in cooling. If a good furnace is available, aluminum can be
melted without any difficulty, although this metal melts at a
higher temperature than any of the metals previously mentioned.

In casting zincs for batteries a separate crucible, used only for
zinc, is very desirable, as the presence of a very small amount of
lead or other impurity will cause the batteries to polarize. A
very good way to make the binding posts is to remove the binding
posts from worn-out dry batteries and place them in the molds in
such a way that the melted zinc will flow around them.

The time required for a casting to solidify varies with the size
and shape of the casting, but unless the pattern is a very large
one about five minutes will be ample time for it to set. The
casting is then dumped out of the mold and the sand brushed off.
The gate can be removed with either a cold chisel or a hacksaw,
and the casting is then ready for finishing.



** Battery Switch [99]

In cases where batteries are used in series and it is desirable to
change the strength and direction of the current frequently, the
following device will be found most convenient. In my own case I
used four batteries, but any reasonable number may be used.
Referring to the figure, it will be seen that by moving the switch
A toward the left the current can be reduced from four batteries
to none, and then by moving the switch B toward the right the
current can be turned on in the opposite

  [Illustration: Battey Switch]

direction to the desired strength. In the various positions of
these two switches the current from each individual cell, or from
any adjacent pair of cells, may be used in either direction.
--Contributed by Harold S. Morton, Minneapolis.



** An Optical Illusion [99]

The engraving shows a perfectly straight boxwood rule laid over a
number of turned brass rings of various sizes. Although the effect
in the illustration

[Illustration: An Optical Illusion]

is less pronounced than it was in reality, it will be noticed that
the rule appears to be bent, but sighting along the rule from one
end will show that it is perfectly straight.

The brass rings also appear distorted. The portions on one side of
the rule do not appear to be a continuation of those on the other,
but that they really are can be proved by sighting in the same
manner as before.
--Contributed by Draughtsman, Chicago.



** New Method of Lifting a Table [99]

To perform this feat effectively the little device illustrated
will be required. To make it take a sheet-iron band, A, 3/4 in.
wide and attach a strap to fasten on the forearm between the wrist
and elbow. Put a sharp needle point, B, through the sheet-iron so
that it extends 3/4 in. outward. Make one of these pieces for each
arm. In lifting the table first show the hands unprepared to the
audience and also a tight table, removing the cover to show that
the surface of the table is not prepared in any way. Then replace
the table,

[Illustration: Table Lifting Device]

rest the hands upon it and at the same time press the needle
points in the arm pieces into the wood of the table, which will be
sufficient to hold it, says a correspondent of the Sphinx. Then
walk down among the audience.



** How to Make a Paddle Boat [100]

A rowboat has several disadvantages. The operation of the oars is
both tiresome and uninteresting, and the oarsman is obliged to
travel, backward.

[Illustration: Paddle Boat]

By replacing the oars with paddles, as shown in the illustration,
the operator can see where he is going and enjoy the exercise much
better than with oars. He can easily steer the boat with his feet,
by means of a pivoted stick in the bottom of the boat, connected
by cords to the rudder.

At the blacksmith shop have a 5/8-in. shaft made, as shown at A,
Fig. 2. It will be necessary to furnish a sketch giving all the
dimensions of the shaft, which should be designed to suit the
dimensions of the boat, taking care that sufficient clearance is
allowed, so that the cranks in revolving will not strike the
operator's knees. If desired, split-wood handles may be placed on
the cranks, to prevent them from rubbing the hands.

The bearings, B, may be made of hardwood, but preferably of iron
pipe filled with melted babbitt. If babbitt is used, either
thoroughly smoke or chalk the shaft or wrap paper around it to
prevent the babbitt sticking. The pieces of pipe may be then
fastened to the boat by means of small pipe straps, such as may be
obtained at any plumber's at a very small cost.

The hubs, C, should be made of wood, drilled to fit the shaft and
mortised out to hold the paddles, D. The covers, E, may be
constructed of thin wood or galvanized iron and should be braced
by triangular boards, as shown in Fig. 1. If galvanized iron is
used, it should be exposed to the weather two or three months
before painting, or the paint will come off, spoiling its
appearance.

[Illustration: Detail of Paddle Boat]



** Peculiar Properties of Ice [100]

Of all the boys who make snowballs probably few know what occurs
during the process. Under ordinary conditions water turns to ice
when the temperature falls to 32 degrees, but when in motion, or
under pressure, much lower temperatures are required to make it a
solid. In the same way, ice which is somewhat below the freezing
point can be made liquid by applying pressure, and will remain
liquid until the pressure is removed, when it will again return to
its original state. Snow, being simply finely divided ice, becomes
liquid in places when compressed by the hands, and when the
pressure is removed the liquid portions solidify and unite all the
particles in one mass. In extremely cold weather it is almost
impossible to make a snowball, because a greater amount of
pressure is then required to make the snow liquid.

This process of melting and freezing under different pressures and
a constant temperature is well illustrated by the experiment shown
in Figs. 1, 2 and 3. A block of ice, A, Fig. 1, is

[Illustration: Experiment with a Block of Ice]

supported at each end by boxes BB, and a weight, W, is hung on a
wire loop which passes around the ice as shown. The pressure of
the wire will then melt the ice and allow the wire to sink down
through the ice as shown in Fig. 2. The wire will continue to cut
its way through the ice until it passes all the way through the
piece, as shown in Fig. 3. This experiment not only illustrates
how ice melts under pressure, but also how it solidifies when the
pressure is removed, for the block will still be left in one piece
after the wire has passed through.

Another peculiar property of ice is its tendency to flow. It may
seem strange that ice should flow like water, but the glaciers of
Switzerland and other countries are literally rivers of ice. The
snow which accumulates on the mountains in vast quantities is
turned to ice as a result of the enormous pressure caused by its
own weight, and flows through the natural channels it has made in
the rock until it reaches the valley below. In flowing through
these channels it frequently passes around bends, and when two
branches come together the bodies of ice unite the same as water
would under the same conditions. The rate of flow is often very
slow; sometimes only one or two feet a day, but, no matter how
slow the motion may be, the large body of ice has to bend in
moving.

This property of ice is hard to illustrate with the substance
itself, but may be clearly shown by sealing-wax, which resembles
ice in this respect. Any attempt to bend a piece of cold
sealing-wax with the hands results in breaking it, but by placing
it between books, as shown on page 65, or supporting it in some
similar way, it will gradually change from the original shape A,
and assume the shape shown at B.



** Return-Call Bell With One Wire [101]

[Illustration: Wiring Diagram]

To use only one wire for a return call bell connect up as shown in
the diagram, using a closed circuit or gravity battery, B. The
current is flowing through both bells all the time, the same as
the coils of a telegraph sounder, but is not strong enough to ring
both connected in series. Pressing either push button, P, makes a
short circuit of that bell and rings the one at the other end of
the line.
--Contributed by Gordon T. Lane, Crafton, Pa.



** Circuit Breaker for Induction Coils [101]

Amateurs building induction coils are generally bothered by the
vibrator contacts blackening, thus giving a high resistance
contact, whenever there is any connection made at all. This
trouble may be done away with by departing from the old
single-contact vibrator and using one with self-cleaning contacts
as shown. An old bell magnet is rewound full of No. 26 double
cotton-covered wire and is mounted

[Illustration: Interrupter for Induction Coil]

upon one end of a piece of thin sheet iron 1 in. by 5 in. as per
sketch. To the other end of the strip of iron is soldered a piece
of brass 1/64 in. by 1/4, in. by 2 in., on each end of which has
been soldered a patch of platinum foil 1/4 in. square.

The whole is connected up and mounted on a baseboard as per
sketch, the contact posts being of 1/4 in. by 1/2 in. brass, bent
into shape and provided with platinum tipped thumb screws. The
advantage of this style of an interrupter is that at each stroke
there is a wiping effect at the heavy current contact which
automatically cleans off any carbon deposit.

In the wiring diagram, A is the circuit breaker; B, the induction
coil, and C, the battery.
--Contributed by A. G. Ward, Wilkinsburg, Pa.



** Spit Turned by Water Power [102]

Many of the Bulgarian peasants do their cooking in the open air
over bonfires. The illustration shows a laborsaving machine in use
which enables the cook to go away and leave meat roasting for an
hour at a time. The

[Illustration: For a Summer Camp]

illustration shows how the spit to which the meat is fastened is
constantly turned by means of a slowly moving water wheel. Some of
our readers may wish to try the scheme when camping out. The
success depends upon a slow current, for a fast-turning wheel will
burn the meat.



** A Short-Distance Wireless Telegraph [102]

The accompanying diagrams show a wireless-telegraph system that I
have used successfully for signaling a distance of 3,000 ft. The
transmitter consists of an induction coil, about the size used for
automobiles, a key or push-button for completing the circuit, and
five dry batteries. The small single-point switch is left open as
shown when sending a message, but when receiving it should be
closed in order that the electric waves from the antenna may pass
through the coherer. The coherer in this case is simply two
electric-light carbons sharpened to a wedge at one end with a
needle

[Illustration: Wiring Diagram for Wireless Telegraph]

connecting the two, as shown. An ordinary telephone receiver is
connected in series with the coherer, as shown. To receive
messages hold the receiver to the ear and close the switch, and
answer by opening the switch and operating the key. --Contributed
by Coulson Glick, Indianapolis.



** Automatic Draft-Opener [102]

A simple apparatus that will open the draft of the furnace at any
hour desired is illustrated. The parts are: A, furnace; B, draft;
C, draft chain; D, pulleys; E, wooden supports; F, vertical lever;
G, horizontal lever; H, cord; I, alarm clock; J, weight. K shows
where and how the draft is regulated during the day, the automatic

[Illustration: Draft Regulator]

device being used to open it early in the morning. The spool on
the alarm clock is fastened to the alarm key by sawing a slit
across the top of the spool and gluing it on. When the alarm goes
off a cord is wound up on the spool and pulls the horizontal lever
up, which releases the vertical lever and allows the weight to
pull the draft open.
--Contributed by Gordon Davis, Kalamazoo, Mich.



** A Window Conservatory [103]

During the winter months, where house plants are kept in the home,
it is always a question how to arrange them so they can get the
necessary light without occupying too much room.

The sketch shows how a neat window conservatory may be made at
small cost that can be fastened on the house just covering a
window, which will provide a fine place for the plants. The frame
(Fig. 2) is made of about 2 by 2-in. material framed together as
shown in Fig. 3. This frame should be made with the three openings
of such a size that a four-paned sash, such as used for a storm
window, will fit nicely in them. If the four vertical pieces that
are shown in Fig. 2 are dressed to the right angle, then it will
be easy to put on the finishing corner boards that hold the sash.

[Illustration: Artistic Window Boxes]

The top, as well as the bottom, is constructed with two small
pieces like the rafters, on which is nailed the sheathing boards
and then the shingles on top and the finishing boards on the
bottom.



** How to Make an Electroscope [103]

An electroscope for detecting electrified bodies may be made out
of a piece of note paper, a cork and a needle. Push the needle
into the cork, and cut the paper in the shape of a small arrow.
Balance the arrow on the needle

[Illustration: Simple Electroscope]

as shown in the sketch, and the instrument will then be complete.
If a piece of paper is then heated over a lamp or stove and rubbed
with a piece of cloth or a small broom, the arrow will turn when
the paper is brought near it.
--Contributed by Wm. W. Grant, Halifax, N. S., Canada.



** Miniature Electric Lighting [104]

Producing electric light by means of small bulbs that give from
one-half to six candle power, and a suitable source of power, is
something that will interest the average American boy.

These circular bulbs range from 1/4 to 2 in. in diameter, and cost
27 cents

[Illustration: FIG. 1]

each complete with base. They are commonly known as miniature
battery bulbs, since a battery is the most popular source of
power. The 1/2-cp. bulbs are usually 2-1/2 volts and take 1/4
ampere of current. It requires about three medium dry cells to
operate it. However, there is now upon the market a battery
consisting of 3 small dry cells connected in series, put up in a
neat case with 2 binding posts, which sells for 25 cents. This is
more economical than dry cells, as it gives about 4 volts and 3
amperes. It will run as large a lamp a 3-1/2 volts, 1 cp., for
some time very satisfactorily. More than one lamp can be run by
connecting the bulbs in parallel, as indicated by Fig. 1, which
shows the special battery with 3 dry cells in the case, and the 2
binding posts for connection with the bulbs. In this case it is
also advisable to connect several batteries in parallel also, so
as to increase the current, but maintain the voltage constant.
Thus the individual cells are in multiple series, i. e., multiples
of series of three. By keeping in mind the ampere output of the
battery and rating of the lamp, one can regulate the batteries as
required. It must be remembered, in this connection, that any
battery which is drawn upon for half of its output will last
approximately three times as long, as if drawn upon for its total
output. Thus, in any system of lamps, it is economical to provide
twice as many batteries as necessary. This also supplies a means
of still maintaining the candle power when the batteries are
partially exhausted, by connecting them in series. However, this
must be done with very great caution, as the lights will be burnt
out if the voltage is too high.

Persons living in the city will find an economical means of
lighting lamps by securing exhausted batteries from any garage,
where they are glad to have them taken away. A certain number of
these, after a rest, can be connected up in series, and will give
the proper voltage.

In conclusion, for battery power: Connecting batteries in series
increases the voltage, and slightly cuts down the current or
amperage, which is the same as that of one battery; while
connecting batteries in parallel increases the amperage, but holds
the voltage the same as that of one cell. Thus, if the voltage and
amperage of any cell be known, by the proper combination of these,
we can secure the required voltage and amperage to light any
miniature lamp. And it might be said that dry cells are the best
for this purpose, especially those of low internal resistance.

[Illustration: FIG.2]

For those having a good water supply there is a more economical
means of maintenance, although the first cost is greater. Fig. 2
shows the scheme. A small dynamo driven by a water motor attached
to a faucet, generates the power for the lights. The cost of the
smallest outfit of the kind is about $3 for the water motor and $4
for the dynamo. This dynamo has an output of 12 watts, and will
produce from 18 to 25 cp., according to the water pressure
obtainable. It is advisable to install the outfit in the basement,
where the water pressure is the greatest, and then lead No. 18 B &
S. double insulated wire wherever needed. The dynamo can also be
used as a motor,

[Illustration: Fig. 3]

and is wound for any voltage up to ten. The winding should
correspond to the voltage of the lamps which you desire to run.
However, if wound for 6 volts, one could run parallel series of
two 3-volt, 1-cp. lamps; making, as in Fig. 3, 11 series, or 22
lights. If wound for 10 volts, it would give 1-1/4 amperes and run
four 6-cp. lamps. Thus, it will be seen that any candle power lamp
can be operated by putting the proper number of lights in each
series, and running the series in parallel. So, to secure light by
this method, we simply turn on the water, and the water
consumption is not so great as might be imagined.

For the party who has electric light in his house there is still
an easier solution for the problem of power. If the lighting
circuit gives 110 volts he can connect eleven 10-volt lamps in
series. These will give 3 cp. each, and the whole set of 11 will
take one ampere of current, and cost about the same as a 32-cp.
lamp, or 1-1/4 cents per hour. Simply connect the miniature
circuit to an Edison plug, and insert in the nearest lamp socket.
Any number of different candle power lamps can be used providing
each lamp takes the same amount of current, and the sum of their
voltages equals the voltage of the circuit used. This arrangement
of small lights is used to produce a widely distributed, and
diffused light in a room, for display of show cases, and for
Christmas trees. Of all these sources of power the two last are
the most economical, and the latter of these two has in its favor
the small initial cost. These lamps are by no means playthings or
experiments, but are as serviceable and practical as the larger
lamps.
--Contributed by Lindsay Eldridge, Chicago.



** How to Make a New Language [105]

Anyone possessing a phonograph can try a very interesting and
amusing experiment without going to any expense. Remove the belt
and replace with a longer one, which can be made of narrow braid
or a number of strands of yarn. The new belt should be long enough
to allow crossing it, thus reversing the machine. This reverses
every sound on the record and changes it to such an extent that
very few words can be recognized.



** How to Make a Cup-and-Saucer Rack [105]

The rack is made of any suitable kind of wood, and the sides, A,
are cut just alike, or from one pattern. The shelves are made in
various widths to fit the sides at the places where they are
wanted. The number of shelves can be varied and to suit the size
of the dishes. Cup hooks are placed on top and bottom shelves. It
is hung on the wall the same as a picture from the molding.
--Contributed by F. B. Emig, Santa Clara, Cal.

[Illustration: Cup-and-Saucer Rack]

Reversing a Small Motor [105]

All that is necessary for reversing the motor is a pole-changing
switch. Connect the two middle posts of the switch with each other
and the two outside posts with each other. Then connect one of the
outside posts of the switch to one brush of the motor and one
middle post to the other brush.

Connect one bar of the switch to one end of the field coil and the
other bar to one pole of the battery, and connect the other pole
of the battery to the other field coil. To reverse the motor,
simply change the switch.

[Illustration: Reverse for a Small Motor]

Referring to the illustration, the letters indicate as follows:
FF, field of motor; BB, brushes of motor; AA, bars of
pole-changing switch; DD, center points of switch; CC, outside
points of switch.
--Contributed by Leonard E. Parker, Plymouth, Ind.



** To Drive Away Dogs [106]

The dogs in my neighborhood used to come around picking up scraps.
After I connected up my induction coil, as shown in the sketch, we
were not bothered with them. A indicates the ground; B, switch;
and C, a bait of meat, or a tempting bone.

[Illustration: Shocking-Machine]

--Contributed by Geo. W. Fry, 903 Vine St., San Jose, Cal.



** An Automatic Lock [106]

The illustration shows an automatic lock operated by electricity,
one cell being sufficient. When the circuit is broken a weight, A,
attached to the end of the armature B, tends to push the other end
of the armature into the screw eye or hook C, which is in the
door, thus locking the door.

To unlock the door, merely push the button E, The magnet then
draws the armature out of the screw eye and the door is unlocked.
The dotted line at D shows the position of the armature when the
circuit is complete and the door unlocked. The weight must be in
proportion to the strength of the magnet. If it is not, the door
will not

[Illustration: Automatic Electric Lock for Doors]

lock, or would remain locked. The button can be hidden, as it is
the key to the lock.
--Contributed by Claude B. Melchior, Hutchinson, Minn.



** Experiment with Two-Foot Rule and Hammer [106]

An example of unstable equilibrium is shown in the accompanying
sketch. All that is needed is a 2-foot rule, a hammer, a piece of
string, and a table or bench. The experiment works best

[Illustration: An Experiment in Equilibrium]

with a hammer having a light handle and a very heavy head.

Tie the ends of the string together, forming a loop, and pass this
around the hammer handle and rule. Then place the apparatus on the
edge of the table, where it will remain suspended as shown.
--Contributed by Geo. P. Schmidt, Culebra, Porto Rico, W. I.



** Simple Current Reverser [107]

On a block of hardwood draw a square (Fig. 1) and drill a hole in
each corner of the square. Fill these holes with mercury and
connect them to four binding posts (Fig. 1).

On another block of wood fasten two wires, as shown in Fig. 2, so
that their ends can be placed in the holes in the first block.
Then connect up with the

[Illustration: Details of Reverser]

motor and battery as in Fig. 3. When the block is placed on with
the big arrow A pointing in the direction indicated in Fig. 3, the
current flows with the small arrows. To reverse turn through an
angle of 90 degrees (Fig. 4). -- Contributed by F. Crawford Curry,
Brockville, Ontario, Canada.



** Alarm Clock to Pull up Furnace Draft [107]

A stout cord, A, is attached to the draft B of the furnace, run
through a pulley, C, in the ceiling and has a window weight, D,
attached at the other end. A small stick is put through a loop in
the cord at about the level of the table top on which the alarm
clock F stands. The other end of stick E is placed under the key G
of the alarm clock. When the alarm rings in the early morning, the
key turns, the stick

[Illustration: Automatic Time Draft-Opener]

falls away, releasing the weight, which pulls the draft open.
--Contributed by Edward Whitney, 18 Gorham St., Madison, Wis.



** How to Transmit Phonograph Music to a Distance [107]

An interesting experiment, and one calculated to mystify anyone
not in the secret, is to transmit the music or speech from a
phonograph to another part of the house or even a greater
distance. For an outdoor summer party the music can be made to
come from a bush, or tree, or from a bed of flowers. The apparatus
is not difficult to construct.

The cut shows the arrangement. Procure a long-distance telephone
transmitter, D, including the mouthpiece, and fasten it to the
reproducer of the phonograph. Also a watch case

[Illustration: The Long-Distance Phonograph]

receiver, R, which fasten to the horn. These parts may be
purchased from any electrical-supply house. Connect two wires to
the transmitter, running one direct to the receiver, and the other
to the battery, thence to a switch, S, and then to the receiver.
The more batteries used the louder will be the sound produced by
the horn, but avoid using too much battery or the receiver is apt
to heat.
--Contributed by Wm. J. Farley, Jr., Camden, N. J.



** How to Make a Telescope [108]

With a telescope like the one here described, made with his own
hands, a farmer boy not many years ago discovered a comet which
had escaped the watchful eyes of many astronomers.

First, get two pieces of plate glass, 6 in. square and 1 in.
thick, and break the corners off to make them round, grinding the
rough edges on a grindstone. Use a barrel to work on, and

[Illustration: Homemade Telescope]

fasten one glass on the top of it in the center by driving three
small nails at the sides to hold it in place. Fasten, with pitch,
a round 4-in. block of wood in the center on one side of the other
glass to serve as a handle.

Use wet grain emery for coarse grinding. Take a pinch and spread
it evenly on the glass which is on the barrel, then take the glass
with the handle and move it back and forth across the lower glass,
while walking around the barrel; also rotate the glass, which is
necessary to make it grind evenly. The upper glass or speculum
always becomes concave, and the under glass or tool convex.

Work with straight strokes 5 or 6 in. in length; after working 5
hours hold the speculum in the sunshine and throw the rays of the
sun onto a paper; where the rays come to a point gives the focal
length. If the glass is not ground enough to bring the rays to a
point within 5 ft., the coarse grinding must be continued, unless
a longer focal length is wanted.

Have ready six large dishes, then take 2 lb. flour emery and mix
in 12 qt. of water; immediately turn the water into a clean dish
and let settle 30 seconds; then turn it into another dish and let
settle 2 minutes, then 8 minutes, 30 minutes and 90 minutes, being
careful not to turn off the coarser emery which has settled. When
dry, turn the emery from the 5 jars into 5 separate bottles, and
label. Then take a little of the coarsest powder, wetting it to
the consistency of cream, and spread on the glass, work as before
(using short straight strokes 1-1/2 or 2 in.) until the holes in
the glass left by the grain emery are ground out; next use the
finer grades until the pits left by each coarser grade are ground
out. When the two last grades are used shorten the strokes to less
than 2 in. When done the glass should be semi-transparent, and is
ready for polishing.

When polishing the speculum, paste a strip of paper 1-1/3 in. wide
around the convex glass or tool, melt 1 lb. of pitch and turn on
to it and press with the wet speculum. Mold the pitch while hot
into squares of 1 in., with 1/4-in. spaces, as in Fig. 1. Then
warm and press again with the speculum, being careful to have all
the squares touch the speculum, or it will not polish evenly. Trim
the paper from the edge with a sharp knife, and paint the squares
separately with jeweler's rouge, wet till soft like paint. Use a
binger to spread it on with. Work the speculum over the tool the
same as when grinding, using straight strokes 2 in. or less.

When the glass is polished enough to reflect some light, it should
be tested with the knife-edge test. In a dark room, set the
speculum against the wall, and a large lamp, L, Fig. 2, twice the
focal length away. Place a large sheet of pasteboard, A, Fig. 2,
with a small needle hole opposite the blaze, by the side of the
lamp, so the light

[Illustration: Detail of Telescope Construction]

from the blaze will shine onto the glass. Place the speculum S,
Fig. 2, so the rays from the needle hole will be thrown to the
left side of the lamp (facing the speculum), with the knife
mounted in a block of wood and edgeways to the lamp, as in K, Fig.
2. The knife should not be more than 6 in. from the lamp. Now move
the knife across the rays from left to right, and look at the
speculum with the eye on the right side of the blade. When the
focus is found, if the speculum is ground and polished evenly it
will darken evenly over the surface as the knife shuts off the
light from the needle hole. If not, the speculum will show some
dark rings, or hills. If the glass seems to have a deep hollow in
the center, shorter strokes should be used in polishing; if a hill
in the center, longer strokes. The polishing and testing done, the
speculum is ready to be silvered. Two glass or earthenware dishes,
large enough to hold the speculum and 2 in. deep, must be
procured. With pitch, cement a strip of board 8 in. long to the
back of the speculum, and lay the speculum face down in one of the
dishes; fill the dish with distilled water, and clean the face of
the speculum with nitric acid, until the water will stick to it in
an unbroken film.

The recipe for silvering the speculum is:

    Solution A:
    Distilled water.............................4 oz.
    Silver nitrate............................100 gr.

    Solution B:
    Distilled water.............................4 oz.
    Caustic stick potash (pure by alcohol)....100 gr.

    Solution C:
    Aqua Ammonia.

    Solution D:
    Sugar loaf................................840 gr.
    Nitric acid................................39 gr.
    Alcohol (Pure).............................25 gr.

Mix solution D and make up to 25 fluid oz. with distilled water,
pour into a bottle and carefully put away in a safe place for
future use, as it works better when old:

Now take solution A and set aside in a small bottle one-tenth of
it, and pour the rest into the empty dish; add the ammonia
solution drop by drop; a dark brown precipitate will form and
subside; stop adding ammonia solution as soon as the bath clears.
Then add solution B, then ammonia until bath is clear. Now add
enough of the solution A, that was set aside, to bring the bath to
a warm saffron color without destroying its transparency. Then add
1 oz. of solution D and stir until bath grows dark. Place the
speculum, face down, in the bath and leave until the silver rises,
then raise the speculum and rinse with distilled water. The small
flat mirror may be silvered the same way. When dry, the silver
film may be polished with a piece of chamois skin, touched with
rouge, the polishing being accomplished by means of a light spiral
stroke.

Fig. 3 shows the position of the glasses in the tube, also how the
rays R from a star are thrown to the eyepiece E in the side of the
tube. Make the tube I of sheet iron, cover with paper and cloth,
then paint to make a non-conductor of heat or cold. Make the
mounting of good seasoned lumber.

Thus an excellent 6-in. telescope can be made at home, with an
outlay of only a few dollars. My telescope is 64 in. long and cost
me just $15, but I used all my spare time in one winter in making
it. I first began studying the heavens through a spyglass, but an
instrument such as I desired would cost $200--more than I could
afford. Then I made the one described, with which I discovered a
new comet not before observed by astronomers.- John E. Mellish.



** How to Make "Freak" Photographs [110]

The "freak" pictures of well-known people which were used by some
daily newspapers recently made everybody wonder how the distorted
photographs were made. A writer in Camera Craft gives the secret,
which proves to be easy of execution. The distortion is
accomplished by the use of prisms, as follows: Secure from an
optician or leaded-glass establishment, two glass prisms, slightly
wider than the lens mount. The flatter they are the less they will
distort. About 20. deg. is a satisfactory angle. Secure them as
shown by the sectional sketch, using strawboard and black paper.
Then make a ring to fit over the lens mount and connect it with
the prisms in such a way as to exclude all light from the camera
except that which passes through the face of the prisms. The inner
surface of this hood must be

[Illustration: Arrangement of Prisms]

dull black. The paper which comes around plates answers nicely. If
the ring which slips over the lens mount is lined with black
velvet, it will exclude all light and hold firmly to the mount,
Place over lens, stop down well after focusing, and proceed as for
any picture.



** Another Electric Lock [110]

The details of the construction of an electrically operated lock
are shown in the illustration. When the door is closed and the
bolt A pushed into position,

[Illustration: Simple Electric Lock]

it automatically locks. To unlock, push the button D, which act
will cause the electromagnet to raise the latch C, when the bolt
may be drawn and the door opened.
--Contributed by A. D. Zimmerman, Boody, Ill.



** How to Mix Plaster of Paris [110]

For the mixing of plaster of Paris for any purpose, add the
plaster gradually to the water, instead of the contrary, says the
Master Painter. Do not stir it, just sprinkle it in until you have
a creamy mass without lumps. Equal parts of plaster and water is
approximately the correct proportion. The addition of a little
vinegar or glue water will retard the setting of the plaster, but
will not preserve its hardening. Marshmallow powder also retards
the setting. In this way the plaster may be handled a long time
without getting hard. If you wish the plaster to set extra hard,
then add a little sulphate of potash, or powdered alum.



** Enlarging with a Hand Camera [111]

Everyone who owns a hand camera has some pictures he would like
enlarged. It is not necessary to have a large camera to do this,
as the process is exceedingly simple to make large pictures from
small negatives with the same hand camera.

A room from which all light may be excluded and a window through
which the light can enter without obstruction from trees or nearby
buildings, with a shelf to hold the camera and a table with an
upright drawing-board attached, complete the arrangement. The back
is taken out of the camera and fitted close against the back of
the shelf, which must be provided with a hole the same size and
shape as the opening in the back of the camera. The negative used
to make the enlarged print is placed in the shelf at A, Fig. 1.
The rays of the clear, unobstructed light strike the mirror, B,
and reflect through the negative, A, through the lens of the
camera and on the board, as shown in Fig. 2. The window must be
darkened all around the shelf.

After placing the negative and focusing the lens for a clear image
on the board, the shutter is set and a bromide paper is placed on
the board. The paper is exposed, developed and fixed by the
directions that are enclosed in the package of bromide papers.

[Illustration: Making Large Pictures with a Small Camera]



** Positioning A Hanging Lamp [111]

Don't pull a lamp hung by flexible cord to one side with a wire
and then fasten to a gas pipe. I have seen a wire become red hot
in this manner. If the lamp hung by a cord must be pulled over,
use a string.

A Curious Compressed Air Phenomenon [111]

Push a pin through an ordinary business card and place the card
against one end of a spool with the pin inside the bore, as shown
in the sketch. Then blow through the spool, and it will be found
that the card will not be blown away, but will remain suspended
without any visible support. This phenomenon is explained by the
fact that the air radiates from the center at a velocity which is
nearly constant, thereby producing a partial vacuum between the
spool and the card. Can the reader devise a practical application
of this contrivance?

[Illustration: Experiment with Spool and Card]



** Simple Switch for Reversing a Current [111]

Take two strips of copper or brass and fasten them together by
means of gutta-percha (Fig. 1); also provide them with a handle.
Saw out a rectangular block about one and one-half times as long
as the brass strips and fasten to it at each end two forked pieces
of copper or brass, as in Fig. 2. Fasten on the switch lever, as
at A and B, Fig. 2, so that it can rotate about these points.
Connect the wires as shown in Fig. 3. To reverse, throw

[Illustration: Simple Current-Reversing Switch]

the lever from one end of the block to the other.
--Contributed by R. L. Thomas, San Marcos, Tex.



** Novel Mousetrap [112]

A piece of an old bicycle tire and a glass fruit jar are the only
materials required for making this trap. Push one end of the tire
into the hole, making sure that there is a space left at the end
so that the mice can get in. Then

[Illustration: A Baitless Trap]

bend the other end down into a fruit jar or other glass jar. Bait
may be placed in the jar if desired, although this is not
necessary.
--Contributed by Geo. Go McVicker, North Bend, Neb.



** Polishing Nickel [112]

A brilliant polish may be given to tarnished nickel by immersing
in alcohol and 2 per cent of sulphuric acid from 5 to 15 seconds.
Take out, wash in running water, rinse in alcohol, and rub dry
with linen cloth.



** Homemade Arc Light [112]

By rewinding an electric-bell magnet with No. 16 wire and
connecting it in series with two electric-light carbons, as shown
in the sketch, a small arc will be formed between the carbon
points when the current is applied. In the sketch, A is the
electric-bell magnet; B, the armature; C C, carbon sockets; D,
carbons, and E E, binding posts. When connected with 10 or 12 dry
batteries this lamp gives a fairly good light.
--Contributed by Morris L. Levy, San Antonio, Tex.

[Illustration: Arc Light]



** Lighting an Incandescent Lamp with an Induction Coil [112]

An incandescent lamp of low candlepower may be illuminated by
connecting to an induction coil in the manner shown in the sketch.
One wire is connected to the metal cap of the lamp and the other
wire is fastened to the glass tip. If the apparatus is then placed
in the dark and the current turned on, a peculiar phosphorescent
glow will fill the whole interior of the lamp. The induction coil
used for this purpose should give a spark about 1/2 in. long or
more.
--Contributed by Joseph B. Bell, Brooklyn.

[Illustration: Geissler Tube]

How to Make a Jump-Spark Coil [113]

The induction coil is probably the most popular piece of apparatus
in the electrical laboratory, and particularly is it popular
because of its use in experimental wireless telegraphy. Ten years
ago wireless telegraphy was a dream of scientists; today it is the
plaything of school-boys and thousands of grown-up boys as well.

Divested of nearly all technical phrases, an induction coil may be
briefly described as a step-up transformer of small capacity. It
comprises a core consisting of a cylindrical bundle of soft-iron
wires cut to proper length. By means of two or more layers of No.
14 or No. 16 magnet wire, wound evenly about this core, the bundle
becomes magnetized when the wire terminals are connected to a
source of electricity.

Should we now slip over this electromagnet a paper tube upon which
has been wound with regularity a great and continuous length of
No. 36 magnet wire, it will be found that the lines of force
emanating from the energized core penetrate the new coil-winding
almost as though it were but a part of the surrounding air itself,
and when the battery current is broken rapidly a second electrical
current is said to be induced into the second coil or secondary.

All or any of the parts of an induction coil may be purchased
ready-made, and the first thing to do is to decide which of the
parts the amateur mechanic can make and which would be better to
buy ready-made. If the builder has had no experience in
coilwinding it would probably pay to purchase the secondary coil
ready-wound, as the operation of winding a mile or more of fine
wire is very difficult and tedious, and the results are often
unsatisfactory. In ordering the secondary it is always necessary
to specify the length of spark desired.

The following method of completing a 1-in. coil illustrates the
general details of the work. The same methods and circuits apply
to small and larger coils. The ready-made secondary is in solid
cylindrical form, about 6 in. long and 2-5/8 in. diameter, with a
hole

[Illustration: Jump-Spark Coil]

through the winding 1-1/4 in. in diameter, as shown in Fig. 1. The
secondary will stand considerable handling without fear of injury,
and need not be set into a case until the primary is completed.
The primary is made of fine annealed No. 24 iron wire cut 7 in. or
8 in. in length, as the maker prefers, and bundled to a diameter
of 7/8 in. The wires may be straightened by rolling two or three
at a time between two pieces of hard wood. If the amateur has
difficulty in procuring this wire, the entire core may be
purchased ready-made.

After the core wires are bundled, the core is wrapped with one or
two layers of manila paper. The straighter the wire the more iron
will enter into the construction of the core, which is desirable.
Beginning half an inch from one end, No. 16 cotton-covered magnet
wire is wound from one end to the other evenly and then returned,
making two layers, and the terminals tied down to the core with
twine. Core and primary are then immersed in boiling paraffine wax
to which a small quantity of resin and beeswax has been added.
This same wax may be used later in sealing the completed coil into
a box. Over this primary is now wrapped one layer of okonite tape,
or same thickness of heavily shellacked muslin. This completed
primary will now allow of slipping into the hole in the secondary.

Should the secondary have been purchased without a case, a wooden
box of mahogany or oak is made, large enough to contain the
secondary and with an inch to spare all around, with room also for
a small condenser; but if it is not convenient to do this work, a
box like that shown in Fig. 2 may be purchased at a small cost. A
7/8-in. hole is bored in the center of one end, through which the
primary core projects 1/8 in. This core is to be used to attract
magnetically the iron head of a vibrating interrupter, which is an
important factor of the coil. This interrupter is shaped as in
Fig. 4, and is fastened to the box in such a way that the vibrator
hammer plays in front of the core and also that soldered
connections may be made inside the box with the screws used in
affixing the vibrator parts to the box. The condenser is made of
four strips of thin paper, 2 yd. long and 5 in. wide, and a
sufficient quantity of tinfoil. When cut and laid in one
continuous length, each piece of tin-foil must overlap the
adjoining piece a half inch, so as to form a continuous electrical
circuit. In shaping the condenser, one piece of the paper is laid
down, then the strip of tin-foil, then two strips of paper and
another layer of foil, and finally the fourth strip of paper. This
makes a condenser which may be folded, beginning at one end and
bending about 6 in. at a time. The condenser is next wrapped
securely with bands of paper or tape, and boiled in pure paraffine
wax for one hour, after which it is pressed under considerable
weight until firm and hard. One of the sheets of tin-foil is to
form one pole of the condenser, and the other sheet, which is
insulated from the first, forms the other pole or terminal. (This
condenser material is purchasable in long strips, ready for
assembling.)

The wiring diagram, Fig. 3, shows how the connections are made.
This method of connecting is suitable for all coils up to 1-1/2
in. spark, but for larger coil better results will be obtained by
using an independent type of interrupter, in which a separate
magnet is used to interrupt the circuit. Besides the magnetic
vibrators there are several other types, such as the mercury
dash-pot and rotary-commutator types, but these will become better
known to the amateur as he proceeds in his work and becomes more
experienced in coil operation.



** Combined Door Bell and Electric Alarm [114]

This device consists of a battery and bell connection to an alarm
clock which also acts as a door bell, the whole being mounted on a
board 18 in. long and 12 in. wide. Referring to the sketch
accompanying this article, the letters indicate as follows: A,
bell; B, battery ; C, switch; D, V-shaped copper strip; E, copper
lever with 1-in. flange turned on one side, whole length, 4 in.;
F, spring to throw lever E down in V-shaped piece to make
connection; G, lever to hold out E when device is used as a door
bell; lines H, go, one from bell, A, and one from battery, B, to
the door; I, shelf for clock.

See that the ring in the alarm key of the clock works easily, so
that when it is square across the clock it will drop down. Fasten
a piece of copper about

[Illustration: Wiring Disgram]

1 in. long to key, then wind the alarm just enough so that the key
stands straight up and down. Place the clock on the shelf and the
key under the flange of lever E. Pull lever G down out of the way
and close the lever on the switch. The alarm key will turn and
drop down, letting lever E drop into the V-shaped piece D and make
connection.

For the door-bell connection close lever on switch C, and put G up
so that D and E do not come in contact. If anyone is ill and you
do not want the bell to ring, open switch C.

The wiring for this device may all be on the back of the board.
The switch and levers are fastened with small screw bolts, which
allows wiring at the back. Saw two spools in half and fasten the
halves to the four corners of the board at the back, and the
apparatus may be put up where one likes.



**v To Build a Small Brass Furnace [115]

Bend a piece of stout sheet iron 23 in. by 12 in. round so that
the inside

[Illustration: Furnace]

diameter is 7 in., and then rivet the seam. Fit in a round piece
of sheet iron for the bottom. Make a hole about the size of a
shilling in the side, 2 in. from the bottom. This is for blowing.

Line the furnace, bottom and sides with fire-clay to a depth of
1/2 in. Use charcoal to burn and an ordinary bellows for blowing,
says the Model Engineer, London. The best blast is obtained by
holding the nozzle of the bellows about an inch from the hole,
instead of close to it.



** Avoid Paper Lamp Shades [115]

Don't wrap paper around a lamp for a shade. You might go away and
forget it and a fire might be started from the heat. Use a glass
or metal shade. That is what they are for.



** Why Gravity Batteries Fail to Work [115]

Many amateur electricians and some professionals have had
considerable trouble with gravity batteries. They

[Illustration: Setting Up a Gravity Battery]

follow directions carefully and then fail to get good results.
The usual trouble is not with the battery itself, but with the
circuit. A gravity battery is suitable only for a circuit which is
normally closed. It is therefore undesirable for electric bells,
induction coils and all other open-circuit apparatus. The circuit
should also have a high resistance. This makes it impractical for
running fan motors, as the motor would have to be wound with fine
wire and it would then require a large number of batteries to give
a sufficiently high voltage.

To set up a gravity battery: Use about 3-1/2 lb. of blue stone, or
enough to cover the copper element 1 in. Pour in water sufficient
to cover the zinc 1/2 in. Short-circuit for three hours, and the
battery is ready for use. If desired for use immediately, do not
short-circuit, but add 5 or 6 oz. of zinc sulphate.

Keep the dividing line between the blue and white liquids about
1/2 in. below the bottom of the zinc. If too low, siphon off some
of the white liquid and add the same amount of water, but do not
agitate or mix the two solutions. This type of battery will give
about 0.9 of a volt, and should be used on a circuit of about 100
milli-amperes.



** A Skidoo-Skidee Trick [116]

In a recent issue or Popular Mechanics an article on "The Turning
Card Puzzle" was described and illustrated. Outside of the
scientific side involved, herein I describe a much better trick.
About the time when the expression "skidoo" first began to be used
I Invented the following trick and

[Illustration: How to Cut the Notches]

called it "Skidoo" and "Skidee," which created much merriment.
Unless the trick is thoroughly understood, for some it will turn
one way, for others the opposite way, while for others it will not
revolve at all. One person whom I now recall became red in the
face by shouting skidoo and skidee at it, but the thing would not
move at all, and he finally from vexation threw the trick into the
fire and a new one had to be made. Very few can make it turn both
ways at will, and therein is the trick.

Take a piece of hardwood 3/8 in. square and about 9 in. long. On
one of the edges cut a series of notches as indicated in Fig. 1.
Then slightly taper the end marked B until it is nicely rounded as
shown in Fig. 2. Next make an arm of a two-arm windmill such as
boys make. Make a hole through the center or this one arm. Enlarge
the hole slightly, enough to allow a common pin to hold the arm to
the end B and not interfere with the revolving arm. Two or three
of these arms may have to be made before one is secured that is of
the exact proportions to catch the vibrations right.

To operate the trick, grip the stick firmly in one hand, and with
the forward and backward motion of the other allow the first
finger to slide along the top edge, the second finger along the
side, and the thumb nail will then vibrate along the notches, thus
making the arm revolve in one direction. To make the arm revolve
in the opposite direction--keep the hand moving all the time, so
the observer will not detect the change which the hand makes
--allow the first finger to slide along the top, as in the other
movement, the thumb and second finger changing places: e. g., In
the first movement you scratch the notches with the thumb nail
while the hand is going from the body, and in the second movement
you scratch the notches with the nail of the second finger when
the hand is coming toward the body, thus producing two different
vibrations. In order to make it work perfectly (?) you must or
course say "skidoo" when you begin the first movement, and then,
no matter how fast the little arm is revolving when changed to the
second movement you must say "skidee" and the arm will immediately
stop and begin revolving in the opposite direction. By using the
magic words the little arm will obey your commands instantly and
your audience will be mystified. If any or your audience presume
to dispute, or think they can do the same let them try it. You
will no doubt be accused of blowing or drawing in your breath, and
many other things in order to make the arm operate. At least it is
amusing. Try it and see.
--Contributed by Charles Clement Bradley Toledo, Ohio.



** Effects of Radium [116]

Radium acts upon the chemical constituents of glass, porcelain and
paper, imparting to them a violet tinge; changes white phosphorus
to yellow, oxygen to ozone, affects photograph plates and produces
many other curious chemical changes.



** Naval Speed Record [116]

On its official trial trip the British torpedo boat destroyer
"Mohawk" attained the record speed of a little over 39 miles an
hour.



** How to Enlarge from Life in the Camera [117]

Usually the amateur photographer gets to a point in his work where
the miscellaneous taking of everything in sight is somewhat
unsatisfying: There are many special fields he may enter, and one
of them is photomicrography. It is usually understood that this
branch of photography means an expensive apparatus. If the worker
is not after too high a magnification, however, there is a very
simple and effective means of making photomicrographs which
requires no additional apparatus that cannot be easily and quickly
constructed at home.

Reproduced with this article is a photograph of dandelion seeds --
a magnification of nine diameters or eighty-one times. The
apparatus which produced this photograph consisted of a camera of
fairly long draw, a means for holding it vertical, a short-focus
lens, and, if possible, but not essential, a means for focusing
that lens in a minute manner. On top of the tripod is the folding
arrangement, which is easily constructed at home with two hinged
boards, an old tripod screw, an old bed plate from a camera for
the screw to fit in, and two sliding brass pieces with sets crews
that may be purchased from any hardware store under the name of
desk sliding braces. To the front board is attached a box,
carrying the lens and the bed of the sliding object carrier, which
can be moved forward and back by the rack and pinion, that also
can be obtained from hardware stores. If the bed for the object
carrier be attached to the bed of the camera instead of to the
front board, the object carrier need have no independent movement
of its own, focusing being done by the front and

[Illustration: Enlargement with a Camera]

back focus of the camera; but this is less satisfactory,
particularly when accurate dimensions are to be determined, says
the Photographic Times. This outfit need not be confined to seeds
alone, but small flowers, earth, chemicals, insects, and the
thousand and one little things of daily life--all make beautiful
subjects for enlarged photographs. These cannot be made by taking
an ordinary photograph and enlarging through a lantern. When a
gelatine dry plate is magnified nine diameters, the grains of
silver in the negative will be magnified also and produce a result
that will not stand

[Illustration: Magnified Nine Diameters]

close examination. Photographs made by photomicrography can be
examined like any other photographs and show no more texture than
will any print.



** Steel Pen Used in Draftsman's Ink Bottle Cork [117]

A steel pen makes an ideal substitute for a quill in the stopper
of the draftsman's ink bottle. The advantage of this substitute is
that there is always one handy to replace a broken or lost pen,
while it is not so with the quill.
--Contributed by George C. Madison, Boston, Mass.



** How to Make a Pilot Balloon [118]
By E. Goddard Jorgensen

Unusual interest is being displayed in ballooning, and as it is
fast becoming the favorite sport many persons would like to know
how to construct a miniature balloon for making experiments. The
following table will give the size, as well as the capacity and
lifting power of pilot balloons:

Diameter.   Cap. in Cu. Ft   Lifting Power.
  5 ft.          65              4 lb.
  6 ft.         113              7 lb.
  7 ft.         179             11 lb.
  8 ft.         268             17 1b.
  9 ft.         381             24 lb.
 10 ft.         523             33 lb.
 11 ft.         697             44 lb.
 12 ft.         905             57 lb.

The material must be cut in suitable shaped gores or segments. In
this article we shall confine ourselves to a 10-ft. balloon. If
the balloon is 10 ft. in diameter, then the circumference will be
approximately 3-1/7 times the diameter, or 31 ft. 5 in. We now
take one-half this length to make the length of the gore, which is
15 ft. 7-1/2 in. Get a piece of paper 15 ft. 7-1/2 in. long and 3
ft. wide from which to cut a pattern, Fig. 1. A line, AB, is drawn
lengthwise and exactly in the middle of the paper, and a line, CD,
is drawn at right angles to AB and in the middle of the paper
lengthways. The intersecting point of AB and CD is used for a
center to ascribe a circle whose diameter is the same as the width
of the paper, or 3 ft. Divide one-quarter of the circle

[Illustration: Pattern for Cutting the Segments]

into 10 equal parts and also divide one-half of the line AB in 10
equal parts. Perpendicular lines are drawn parallel with the line
CD intersecting the division points made on the one-half line AB.
Horizontal and parallel lines with AB are drawn intersecting the
division points made on the one-quarter circle and intersecting
the perpendicular line drawn parallel with CD. A line is now drawn
from B to E and from E to F, and so on, until all the intersecting
lines are touched and the point C is reached. This will form the
proper curve to cut the pattern. The paper is now folded on the
line AB and then on the line CD, keeping the marked part on the
outside. The pattern is now cut, cutting all four quarters at the
same time, on the curved line from B to C. When the paper is
unfolded you will have a pattern as shown in Fig. 2. This pattern
is used to mark the cloth, and after marked is cut the same shape
and size.

The cloth segments are sewed together, using a fine needle and No.
70 thread, making a double seam as shown in Fig. 3. When all seams
are completed you will have a bag the shape shown in Fig. 4. A
small portion of one end or a seam must be left open for
inflating. A small tube made from the cloth and sewed into one end
will make a better place for inflating and to tie up tightly.

It is now necessary to varnish the bag in order to make it retain
the gas. Procure 1 gal. of the very best heavy body, boiled
linseed oil and immerse the bag in it. The surplus oil is squeezed
out by running the bag through an ordinary clothes wringer several
times. The bag is now placed in the sun for a thorough drying. Put
the remaining oil in a kettle with 1/8 lb. of beeswax and boil
well together. This solution is afterward diluted with turpentine
so it will work well. When the bag is dry apply this mixture by
rubbing it on the bag with a piece of flannel. Repeat this
operation four times,

[Illustration: Sewing Segments Together]

being sure of a thorough drying in the sun each time. For indoor
coating and drying use a small amount of plumbic oxide. This will
dry rapidly in the shade and will not make the oil hard.

Fill the bag with air by using a pair of bellows and leave it over
night. This test will show if the bag is airtight. If it is not
tight then the bag needs another rubbing. The next operation is to
fill the bag with gas.

Hydrogen gas is made from iron and sulphuric acid. The amounts
necessary for a 10-ft. balloon are 125 lb. of iron borings and 125
lb. of sulphuric acid. 1 lb. of iron, 1 lb. of sulphuric acid and
4 lb. of water will make 4 cu. ft. of gas in one hour. Secure two
empty barrels of about 52 gal. capacity and connect them, as shown
in Fig. 5, with 3/4-in. pipe. In the barrel, A, place the iron
borings and fill one-half full of clear water. Fill the other
barrel, B, with water 2 in. above the level of the water in barrel
A. This is to give a water pressure head against foaming when the
generator is in action. About 15 lb. of lime should be well mixed
with the water in the barrel B. All

[Illustration: FIG. 5; The Hydrogen Generator]

joints must be sealed with plaster of Paris. Pour in one-half of
the acid into the barrel, A, with the iron borings. The barrels
are kept tight while the generation is going on with the exception
of the outlet, C, to the bag. When the action is stopped in the
generator barrel, A, let the solution run out and fill again as
before with water and acid on the iron borings. The outlet, C,
should be always connected with the bag while the generator is in
action. The 3/4-in. pipe extending down into the cooling tank, B,
should not enter into the water over 8 in. When filled with gas
the balloon is ready for a flight at the will of the operator.



** How to Clean a Clock [119]

It is very simple to clean a clock, which may sound rather absurd.
For an amateur it is not always necessary to take the clock to
pieces. With a little care and patience and using some benzine, a
clean white rag, a sable brush and some oil a clock can be cleaned
and put into first-class running order. The benzine should be
clean and free from oil. You can test benzine by putting a little
on the back of the hand; if it is good it will dry off, leaving
the hand quite clean, but if any grease remains on the hand, it is
not fit to use.

The oil should be of the very best that can be procured. Vegetable
oils should never be used. Clock oil can be procured from your
druggist or jeweler.

All loose dirt should be removed from the works by blowing with
bellows, or a fan, or dusting with a dry brush; in the latter case
great care should be exercised not to injure any of the parts. Dip
the brush in the benzine and clean the spindles and spindle holes,
and the teeth of the escapement wheel. After washing a part, wipe
the brush on the rag and rinse in the benzine; this should be
repeated frequently, until no more dirt is seen.

When the clock has dried, oil the spindle holes carefully; this
may be done with a toothpick or a sliver of woodcut to a fine
point. Oil the tooth of the escapement wheel slightly, using a
fine brush.



** How to Make Blueprint Lantern Slides [120]

Lantern slides of a blue tone that is a pleasing variety from the
usual black may be made from spoiled or old plates which have not
been developed, by fixing, washing well and then dipping five
minutes in the following solution:

    A. Green Iron ammonium citrate    150 gr.
       Water                            1 oz.

    B. Potassium ferrocyanide          50 gr.
       Water                            1 oz.

Prepare the solutions separately and mix equal parts for use, at
the time of employment. Dry the plates in the dark, and keep in
the dark until used. Printing is done in the sun, and a vigorous
negative must be used, says the Moving Picture World. Exposure, 20
to 30 minutes. Wash 10 minutes in running water and dry. Brown or
purple tones may be had by sensitizing with the following solution
instead of the above:

    Distilled water            1 oz.
    Sliver nitrate            50 gr.
    Tartaric or citric acid  1/2 oz.

Bathe the plates 5 minutes, keeping  the fingers out of the
solution, to avoid blackened skin. Dry in the dark. Print to
bronzing under a strong negative; fix in hypo, toning first if
desired.



** A Substitute for a Ray Filter [120]

Not many amateur photographers possess a ray filter. A good
substitute is to use the orange glass from the ruby lamp. This can
be held in position in front of the lens with a rubber band. A
longer exposure will be necessary, but good cloud effects can be
procured in this manner.



** Electric Lamp Experiments [120]

Incandescent electric lamps can be made to glow so that they may
be seen in a dark room by rubbing the globe on clothing or with a
paper, leather or tinfoil and immediately holding near a 1/2-in.
Ruhmkorff coil which is in action but not sparking. The miniature
16 cp., 20 and 22-volt lamps will show quite brilliantly, but the
110-volt globes will not glow. When experimenting with these
globes everything should be dry. A cold, dry atmosphere will give
best results.

*     *     *     *     *     *     *


[Illustration: Annual Regatta, Port Melbourne, Australia]



** How to Make a Simple Wireless Telegraph [121]
By ARTHUR E. JOERIN

An efficient wireless-telegraph receiving apparatus for distances
up to 1,000 ft. may be constructed in the following manner: Attach
a watchcase telephone receiver to a dry cell, or battery, of any
make. The negative pole, or zinc, of the cell is connected to a
ground wire. This is done by attaching to a gas or water pipe. The
positive pole, or carbon, of the cell is connected to the aerial
line. This aerial collector can be made in various ways, either by
using a screen wire or numerous wires

[Illustration: For Distances up to 1000 Feet]

made in an open coil and hung in the air. File a V-shaped groove
in the upper end of the carbon of the cell. Attach a small bent
copper wire in the binding post that is attached to the zinc of
the cell. In the bend of this wire and the V-shaped groove filed
into the carbon, lay a needle. This will complete the receiving
station. Use a spark coil in connection with a telegraph key for
the sending station, making a ground with one wire, and have the
other connected with another aerial line.

By connecting the telephone receiver to the cell and at the same
time having a short circuit a receiving station is made. As the
telephone offers a high resistance, part of the current will try
to take the shorter high resistance through the needle. If the
waves strike across the needle, the resistance is less, and thus
less current travels through the telephone receiver. If the wave
ceases, the resistance between the needle and the carbon is
increased, and as less current will flow the short way, it is
compelled to take the longer metallic way through the windings of
the receiver, which will cause the clickings that can be heard.



** To Preserve Putty [121]

Putty, when left exposed to the air, will soon become dry and
useless. I have kept putty in good condition for more than a year
by placing it in a glass jar and keeping it entirely covered with
water.



** How to Make a Small Storage Battery [121]

The cell of a storage battery consists of two plates, a positive
and a negative, made of lead and placed in a dilute solution of
sulphuric acid. Large batteries made of large cells have a great
number of plates, both positive and negative, of which all
positive plates are connected to one terminal and the negative
plates to the other terminal. The storage cell, as described
below, is the right size to be charged by a few gravity cells and
is easily made.

Secure a piece of 1-3/4-in. lead pipe, 5 in. long, and cut both
ends smooth and square with the pipe. Solder a circular disk of
lead to one end, forming a cup of the pipe. As this cup must hold
the sulphuric acid it must be perfectly liquid-tight. It is also
necessary to get another lead pipe of the same length but only
3/4-in. in diameter. In this pipe should be bored as many 1/8-in.
holes

[Illustration: Battery]

as possible, except for about 1 in. on each end. One end of this
tube is hammered together as shown at A in the sketch to make a
pocket to hold the paste. This, of course, does not need to be
watertight.

A box of wood is made to hold the larger tube or cup. This box can
be square, and the corners left open around the cup can be filled
with sawdust. A support is now made from a block of wood to hold
the tube, B, in place and to keep it from touching the cup C. This
support or block, D, is cut circular with the same diameter as the
lead cup C. The lower portion of the block is cut away so it will
just fit inside of the cup to form a stopper. The center of this
block is now bored to make a hole the same size as the smaller
lead pipe. Place the lead pipe in the hole and immerse it in
smoking hot paraffine wax, and leave it until the wood has become
thoroughly saturated with the hot wax. Use care to keep the wax
from running on the lead at any place other than the end within
the wood block. Two binding-posts should be attached, one to the
positive, or tube B, and the other to the negative, or tube C, by
soldering the joint.

A paste for the positive plate is made from 1 part sulphuric acid
and 1 part water with a sufficient amount of red lead added to
make of thick dry consistency. When mixing the acid and water, be
sure to add the acid to the water and not the water to the acid.
Also remember that sulphuric acid will destroy anything that it
comes in contact with and will make a painful burn if it touches
the hands. Stir the mixture with a stick and when a good dry paste
is formed, put it into the smaller tube and ram it down until the
tube is almost filled. The paste that may have come through the
holes is scraped off and the tube set aside to dry. The large tube
or cup is filled with a diluted solution of sulphuric acid. This
solution should be about one-twelfth acid. The cell is now
complete and ready for storing the current.

The cell may be charged with three gravity cells. These are
connected in series and the positive terminal binding-post on the
storage cell is connected to the wire leading from the copper
plate in the gravity cell. The other plate is connected to the
zinc. The first charge should be run into the cell for about one
week and all subsequent charges should only take from 10 to 12
hours.



** Fitting a Plug in Different Shaped Holes [122]

A certain king offered to give the prince his liberty if he could
whittle a plug that would fit four different shaped holes, namely:
a square hole, a round one, an oblong one and a triangular one,
says the Pathfinder. A broomstick was used to make the plug and it
was whittled in the shape shown

[Illustration: Fits Four Different Shaped Holes]

in Fig. 1. The holes in the different places as shown in Fig. 2,
were fitted by this one plug.



** How to Make a Lightning Arrester [122]

Secure a piece of wood about 3-1/2 in. square that will furnish a
nice finish and round the corners and make a small rounding edge
as shown in the sketch. From a piece of brass 1/16 in. thick cut
two pieces alike, A and B, and match them together, leaving about
1/16 in. between their upper edges and fasten them to the wood
with binding-posts. The third piece of brass, C, is fitted

[Illustration: Lightning Arrester]

between the pieces A and B allowing a space of 1/16-in. all around
the edge. One binding-post and a small screw will hold the piece
of brass, C, in place on the wood. The connections are made from
the line wires to the two upper binding-posts and parallel from
the lower binding-posts to the instrument. The third binding-post
on C is connected to the ground wire. Any heavy charge from
lightning will jump the saw teeth part of the brass and is
grounded without doing harm to the instruments used. --Contributed
by Edwin Walker, Chicago, Ill.



** A Home-Made Punt [123]

A flat bottom boat is easy to make and is one of the safest boats,
as it is not readily overturned. It has the advantage of being
rowed from either end, and has plenty of good seating capacity.

This punt, as shown in Fig. 1, is built 15 ft. long, about 20 in.
deep and 4 ft. wide. The ends are cut sloping for about 20 in.
back and under. The sides are each made up from boards held
together with battens on the inside of the boat near the ends and
in the middle. One wide board should be used for the bottom piece.
Two pins are driven in the top board of each side to serve as
oarlocks.

The bottom is covered with matched boards not over 5 in. wide.
These pieces are placed together as closely as possible, using
white lead between the joints and nailing them to the edges of the
side boards and to a keel strip that runs the length of the punt,
as shown in Fig. 2. Before nailing the boards place lamp wicking
between them and the edges of the side boards. Only galvanized
nails should be used. In order to make the punt perfectly
watertight it is best to use the driest lumber obtainable. At one
end of the punt a skag and a rudder can be attached as shown in
Fig. 3.

[Illustration: Easy to Build and Safe to Use]



** Photographers' Printing Frame Stand [123]

When using developing papers it is always bothersome to build up
books or

[Illustration: Adjustable to Any Height]

small boxes to make a place to set the printing frame in front of
the light. Details for making a small stand that is adjustable to
any desired height are shown in the sketch. In Fig. 1 is shown the
construction of the sliding holder. A piece of 1/4-in. gas pipe,
A, is cut 1 in. long and fitted with a thumbscrew, B. The piece of
pipe is soldered to the middle on the back side of a piece of
metal that is about 4 by 4-1/2 in. with its lower edge turned up
to form a small shelf as shown at C. The main part of the stand is
made by inserting a 5/16-in. rod tightly into a block of hard
maple wood that is 1 in. thick and 3-1/2 in. square (Fig 2). The
pipe that is soldered to the metal support will slide up and down
the rod and the thumbscrew can be set to hold it at the desired
point.



** Heat and Expansion [124]

Take an electric light bulb from which the air has not been
exhausted and immerse it in water and then break off the point. As
there is a vacuum in the bulb it will quickly fill with water.
Shake the bulb gently until a part of the water is out and then
screw the bulb into a socket with the point always downward. Apply
the current and the heated air inside will soon expand and force
the water out with great rapidity. Sometimes this experiment can
be done several times by using the same bulb.
--Contributed by Curtiss Hill, Tacoma, Wash.



** Photographing a Streak of Lightning [124]

The accompanying illustration is a remarkable photograph of a
streak of lightning. Many interesting pictures of this kind can be
made during a storm at night. The camera is set in a place where
it will not get wet and left standing with the shutter open and
the plate ready for the exposure. Should a lightning streak appear
within the range of the lens it will be made on the plate, which
can be developed in the usual manner. It will require some
attention to that part of the sky within the range of the lens so
as to not make a double exposure by letting a second flash enter
the open lens.
--Contributed by Charles H. Wagner.

*     *     *     *     *

Borax may be used as a solvent for shellac gum.

*     *     *     *     *



** How to Make a Small Single-Phase Induction Motor [124]
By C. H. Bell

The following notes on a small single-phase induction motor,
without auxiliary phase, which the writer has made, may be of
interest to some of our readers, says the Model Engineer. The
problem to be solved was the construction of a motor large enough
to drive a sewing machine or very light lathe, to be supplied with
110-volt alternating current from a lighting circuit, and to
consume, if possible, no more current than a 16-cp. lamp. In
designing, it had to be borne in mind that, with the exception of
insulated wire, no special materials could be obtained.

[Illustration: Motor]

The principle of an induction motor is quite different from that
of the commutator motor. The winding of the armature, or "rotor,"
has no connection with the outside circuit, but the current is
induced in it by the action of the alternating current supplied to
the winding of the field-magnet, or "stator." Neither commutator
nor slip rings are required, and all sparking is avoided.
Unfortunately, this little machine is not self-starting, but a
slight pull on the belt just as the current is turned on is all
that is needed, and the motor rapidly gathers speed provided no
load is put on until it is in step with the alternations of the
supply. It then runs at constant speed whether given much or
little current, but stops if overloaded for more than a few
seconds.

The stator has four poles and is built up of pieces of sheet iron
used for stove pipes, which runs about 35 sheets to the inch. All
the pieces are alike and cut on the lines with the dimensions as
shown in Fig. 1, with the dotted line, C, to be filed out after
they are placed together. Each layer of four is placed with the
pointed ends of the pieces alternately to the right and left so as
to break joints as shown in Fig. 2. The laminations were carefully
built up on a board into which heavy wires had been driven to keep
them in place until all were in position and the whole could be
clamped down. In the middle of the pieces 1/4-in. holes, B, were
then drilled and 1/4-in. bolts put in and tightened up, large
holes being cut through the wood to enable this to be done. The
armature tunnel was then carefully filed out and all taken apart
again so that the rough edges could be scraped off and the
laminations given a thin coat of shellac varnish on one side.
After assembling a second time, the bolts were coated with shellac
and put into place for good. Holes 5-32 in. in diameter were
drilled in the corners, A, and filled with rivets, also varnished
before they were put in. When put together they should make a
piece 2 in. thick.

This peculiar construction was adopted because proper stampings
were not available, and as every bit of sheet iron had to be cut
with a small pair of tinners' snips, it was important to have a
very simple outline for the pieces. They are not particularly
accurate as it is, and when some of them got out of their proper
order while being varnished, an awkward job occurred in the magnet
which was never entirely corrected. No doubt some energy is lost
through the large number of joints, all representing breaks in the
magnetic circuit, but as the laminations are tightly held together
and the circuit is about as compact as it could possibly be,
probably the loss is not as great as it would appear at first
sight.

The rotor is made of laminations cut from sheet iron, as shown in
Fig. 3, which were varnished lightly on one side and clamped on
the shaft between two nuts in the usual way. A very slight cut was
taken in the lathe afterwards to true the circumference. The shaft
was turned from 1/2-in. wrought iron, no steel being obtainable,
and is shown with dimensions in Fig. 4. The bearings were cast of
babbitt metal, as shown in Fig. 5, in a wooden mold and bored to
size with a twist drill in the lathe. They are fitted with
ordinary wick lubricators. Figures 6 and 7 are sections showing
the general arrangement of the machine.

The stator is wound full with No. 22 double cotton-covered copper
wire,

[Illustration: Motor]

about 2-1/2 lb. being used, and the connections are such as to
produce alternate poles--that is, the end of the first coil is
joined to the end of the second the beginning of the second to the
beginning of the third, and the end of the third to the end of the
fourth, while the beginnings of the first and fourth coils connect
to the supply.

The rotor is wound with No. 24 double cotton-covered copper wire,
each limb being filled with about 200 turns, and all wound in the
same direction. The four commencing ends are connected together on
one side of the rotor and the four finishing ends are soldered
together on the other. All winding spaces are carefully covered
with two layers of cambric soaked in shellac, and as each layer of
wire was wound, it was well saturated with varnish before the next
was put on.

This type of motor has drawbacks, as before stated, but if regular
stampings are used for the laminations, it would be very simple to
build, having no commutator or brushes, and would not easily get
out of order. No starting resistance is needed, and as the motor
runs at constant speed, depending upon the number of alternations
of the supply, a regulating resistance is not needed.



** Carbolic Acid Burns [126]

The pain of carbolic acid burns can be relieved promptly by
washing with alcohol, if applied immediately. If too late for
alcohol to be of use, brush with water containing saturated
solution of picric acid.



** How to Make a Paper Book Cover [126]

Book covers become soiled in handling and especially school books.
Various methods are applied for making a temporary cover that will
protect the book cover. A paper cover can be quickly made by using
a piece of paper larger than both covers on the book when they are
open. Fold the paper on the long dotted line, as shown in Fig. 1.
When the folds are made the paper should then be just as wide as
the book cover is high. The ends are then folded on the short
dotted lines, which will make it appear as shown in Fig. 2. The
paper thus folded is placed on the book cover as shown in Fig. 3.
--Contributed by C. E. McKinney, Jr., Newark, N. J.

[Illustration: To Protect Book Covers]



** How to Make Lantern Slides [127]

The popularity of lantern slides, and especially of colored ones,
as a means of illustrating songs, has caused so large a demand for
this class of work that almost any amateur may take up slide
making at a good profit. The lantern slide is a glass plate,
coated with slow and extremely fine-grained emulsion. The size is
3-1/4 by 4 in. A lantern slide is merely a print on a glass plate
instead of on paper. Lantern slides can be made in two different
ways. One is by contact, exactly the same as a print is made on
paper, and the other by reduction in the camera. In making slides
by contact, select the negative and place it in the printing frame
and put the lantern plate upon it, film to film. Clamp down the
back and expose just as in making a print. A good method of
exposing is to hold a lighted match about 3 in. from the frame for
three or more seconds according to the density.

Development is carried on in the same manner as with a negative.
The image should appear in. about a minute, and development should
be over in three or four minutes. If the exposure has been
correct, the high lights will stay white throughout the
development and will come out as clear glass after fixing. It is
best to use the developers recommended by the manufacturer of the
plates used, the formulas being found in each package of plates.
It is best, also, to use a plain fixing bath, which must be fresh
and kept as cool as possible in hot weather.

The lantern-slide film that is new on the market can be handled in
the same manner as the glass-plate slide, except that the binding
is different. The results are the same and the slides are not so
bulky to handle. Being unbreakable, they are much used by
travelers. The manner of binding them for use in a lantern is
described on the circular enclosed with the film.

[Illustration: The Camera as It is Arranged in Front of the Window
for Reducing the Size of a Picture, and the Method of Binding the
Slides]

When the negative is larger than the lantern-slide plate, and it
is desirable to reduce the entire view upon the slide, a little
extra work will be necessary. Select a room with one window, if
possible, and fit a light-proof frame into it to keep out all
light with the exception of a hole in which to place the negative,
as shown in Fig. 1. Unless this hole is on a line with the sky it
will be necessary to place a sheet of white cardboard at an angle
of 45 deg. on the outside of the frame to reflect the light
through the negative as shown in Fig. 2. Make or secure an inside
kit to place in the plate holder of your camera to hold the
lantern slide plate as shown in Fig. 3. Draw lines with a pencil,
outlining on the ground glass of the camera the size of the
lantern slide plate, and in the place where the plate will be in
the plate holder when placed in position in the camera. This will
enable you to focus to the proper size. Place the camera in front
of the hole in the frame, place the negative in the hole and focus
the camera for the lantern slide size. Expose with a medium stop
for about 20 seconds and treat the plate the same as with the
contact exposure.

When dry the lantern slide plate may be tinted any color by means
of liquid colors. These can be purchased from any photo material
store. In coloring the slide plate it is only necessary to moisten
the gelatine film from time to time with a piece of cloth dampened
in water. The colors may then be spread evenly with a soft brush,
which should be kept in motion to prevent spots.

The slide is put together by placing a mat made of black paper, as
shown in Fig. 4, on the gelatine side of the lantern slide, A,
Fig. 5, and then a plain glass, B, over the mat, C, and the three
bound together with passepartout tape, D. Contrasty negatives make
the best slides, but the lantern slide plate should be made
without any attempt to gain density.



** HOW TO MAKE A PORCH SWING CHAIR [128]

The material needed for making this porch swing chair are two
pieces of round wood 2-1/2 in. in diameter and 20 in. long, and
two pieces 1-1/4 in. in diameter and 40 in. long. These longer
pieces can be made square, but for appearance it is best to have
them round or square with the corners rounded. A piece of canvas,
or other stout cloth, 16 in. wide and 50 in. long, is to be used
for the seat. The two short pieces of wood are used for the ends
of the chair and two 1-in. holes are bored in each end of them
1-1/2 in. from the ends, and between the holes and the ends
grooves are cut around them to make a place to fasten ropes, as
shown at B, Fig. 1. The two longer pieces are used for the sides
and a tenon is cut on each end of them to fit in the 1-in. holes
bored in the end pieces, as shown at A, Fig. 1. The canvas is now
tacked on the end pieces and the pieces given one turn before
placing the mortising together.

[Illustration: Swing Chair]

The chair is now hung up to the porch ceiling with ropes attached
to a large screw eye or hook. The end of the chair to be used for
the lower part is held about 16 in. from the floor with ropes
direct from the grooves in the end pieces to the hook. The upper
end is supported by using a rope in the form of a loop or bail, as
shown in Fig. 2. The middle of the loop or bail should be about 15
in. from the end piece of the chair. Another rope is attached to
the loop and through the hook and to a slide as shown. This will
allow for adjustment to make the device into a chair or a hammock.
--Contributed by Earl R. Hastings, Corinth, Vt.



** How to Find the Blind Spot in the Eye [129]

Make a small black circular dot 1/2 in. in diameter on a piece of
cardboard and about 3 in. from the center of this dot draw a star.
Hold the cardboard so that the star will be directly in front of
one eye, while the dot will be in front of the other. If the star
is in front of the left eye, close the right eye and look steadily
at the star while you move the cardboard until the point is
reached where the dot disappears. This will prove the presence of
a blind spot in a person's eye. The other eye can be given the
same experiment by turning the cardboard end for end. The blind
spot does not indicate diseased eyes, but it simply marks the
point where the optic nerve enters the eyeball, which point is not
provided with the necessary visual end organs of the sight, known
as rods and cones.



** Beeswax Substitute [129]

A wax from the rafie palm of Madagascar is being used as a
substitute for beeswax.



** Home-Made Water Wheel Does Family Washing [129]

[Illustration: Water Wheel]

The accompanying sketch illustrates a very ingenious device which
does the family washing, as well as to operate other household
machines. A disk 1 in. in thickness and 10 in. in diameter was cut
from a piece of rough board, and on its circumference were nailed
a number of cup-shaped pieces cut from old tin cans. A hole was
then bored through the center of the disk and an old piece of iron
rod was driven through to form a shaft. Two holes were then bored
opposite each other through the sides of a wooden box in which the
disk was placed, allowing the shaft to project through the holes.
A small grooved wooden pulley was driven tightly on one of the
projecting ends of the shaft. The top of the box was then tightly
closed and a hole, large enough to admit the nozzle of a garden
hose, was bored so that the jet of water would flow upon the tin
buckets that were nailed to the circumference of the wheel or
disk. Another hole was bored in the bottom of the box large enough
to allow the waste water to run away freely. A belt, made from an
ordinary sash cord, was run from the small pulley on the
waterwheel to a large pulley, as shown in Fig. 1. A pitman was
attached to the large pulley, which operates the washing machine
by its reciprocating motion, and the length of the stroke is
adjusted by moving the position of the hinge joint on the arm of
the washing machine, as shown in Fig. 2. The pressure at the
nozzle is about 20 lb. per square inch, and is sufficient to drive
the waterwheel under all ordinary circumstances.
--Contributed by P. J. O'Gara, Auburn, Cal,



** An Optical Illusion [130]

When looking at the accompanying sketch you will say that the
letters are alternately inclined to the right and left. They are
not so and can be proved by measuring the distance of the top and
bottom of any vertical strokes from the edge of the entire block.
They will be found to be exactly the same distance. Or take any of
the horizontal strokes of the four letters and see how far their
extremities are from the top and bottom of the entire block. It
will be found that a line joining the extremities of the strokes
are strictly parallel to the top or bottom and that they are not
on a slant at all. It is the slant of the numerous short lines
that go to make up the letter as a whole that deceives the eye.

[Illustration: Illusion]



** Home-Made Micrometer [130]

It often becomes necessary to find the thickness of material so
thin, or inconvenient to measure, that a rule or other measuring
device will not serve the purpose. A simple, fairly accurate, and
easily made apparatus of the micrometer form may be constructed as
shown by the accompanying sketch. Secure a common iron or brass
bolt about 1/4-in. in diameter and about 2-1/2 in. long, with as
fine a thread as possible, and the thread cut to within a short
distance of the head of the bolt. The head of the bolts should
have a slot cut for the use of a screwdriver. Clamp together two
blocks of wood with square corners which are about 1 in. wide, 3/4
in. thick and 2-1/2 in. long and fasten them together with small
pieces nailed across the ends. The width of the blocks will then
be about 2 in. Bore a 1/4-in. hole through the center of the
blocks in the 2 in. direction. Remove the clamp and set the nut
into one of the blocks, so that the hole will be continuous with
the hole in the wood. Cut out a piece from the block combination,
leaving it shaped like a bench, and glue the bottoms of the legs
to a piece of thin board about 2-1/2 in. square for a support.

Solder one end of a stiff wire that is about 2 in. long to the
head of the bolt at right angles to the shaft, and fix a disc of
heavy pasteboard with a radius equal to the length of the wire,
and with its circumference graduated into equal spaces, to serve
in measuring revolutions of the end of the wire, to the top of the
bench. Put the bolt in the hole, screwing it through the nut,

[Illustration: Micrometer]

and the construction is complete. The base is improved for the
measuring work by fastening a small piece of wood on the board
between the legs of the bench. A small piece of metal is glued on
this piece of wood at the point where the bolt meets it.

Find the number of threads of the screw to the inch by placing the
bolt on a measuring rule, and counting the threads in an inch of
its length. The bolt in making one revolution will descend a
distance equal to the distance between the threads.

The device is used by placing the object whose thickness is to be
measured on the base under the bolt, and screwing the bolt down
until its end just touches the object, then removing the object,
and screwing the bolt down until its end just touches the base,
carefully noting while doing so the distance that the end of the
wire moves over the scale. The part of a rotation of the bolt, or
the number of rotations with any additional parts of a rotation
added, divided by the number of threads to the inch, will be the
thickness of the object. Quite accurate measurements may be made
with this instrument, says the Scientific American, and in the
absence of the expensive micrometer, it serves a very useful
purpose.



** Another Electric Lamp Experiment [131]

Break a portion of the end off from a 16-cp. globe that has been
thrown away as useless. Shake the globe until all the filament is
broken away, leaving only the ends of the platinum wire exposed.
Screw the globe into a socket that sets upright and fill it with
salt water. Make one connection to the socket from the positive
wire of a 110 volt circuit and the other to a ground. When the
current is turned on small stars will be seen in the globe, which
show up fine at night.
--Contributed by Lindsay McMillan, Santa Maria, Oal.



** Removing Ink Stains [131]

Two or three applications of milk which are wiped up with a dry
cloth will remove india ink spots on carpets.



** Feat of Balancing on Chairs [131]

[Illustration: For Boys Balanacing]

Among the numerous physical exercises is the feat of balancing on
the two rear legs of a chair while one foot rests on the front
part of the seat and the other on the back of the chair. This may
appear to be a hard thing to do, yet with a little practice it may
be accomplished. This exercise is one of many practiced by the
boys of a boys' home for an annual display given by them. A dozen
of the boys will mount chairs at the same time and keep them in
balance at the word of a commanding officer.



** How to Make a Merry-Go-Round Swing [131]

A 6 by 6-in. piece of wood 12 ft. long is used for the center
pole. Bore a 3/4-in. hole in each end to a depth of 6 in. Place a
3/4-in. bolt in each hole, the bolt being long enough to protrude
2 in. beyond the end of the wood. Short pieces of wood are nailed
on the center pole about 2 ft. from the end that is to be used for
the bottom. This should form a hub on which to place the inner
ends of the extending spokes that hold the platform. The spokes
are made from twelve pieces of 2 by 4-in. material 12 ft. long.

Usually a wheel can be found in a scrap pile suitable to place on
the pin that is in the top end of the center pole. The wheel
should be open

[Illustration: Side and Top View]

or have spokes. This wheel is used to attach wires for guying. The
bottom pin in the center pole is placed in a hole that is bored
into a block of wood about 12-in. square and 3 or 4 in. thick. A
piece of sheet metal should be drilled and placed on the pin
between the block and end of the pole to make a smooth bearing.
The center pole is now placed in position and guyed with six wires
that are about 35 ft. long. Stakes are driven into the ground and
the wires fastened to them and to the wheel at the top end of the
pole. Care should be taken when attaching the wires to get the
center pole to stand perpendicular. Twelve hooks should be placed
at equal distances around the center pole about 1 ft. from the top
end. Wires are fastened to these hooks and to the twelve 2 by
4-in. pieces used for the spokes. The wires should be tied around
each spoke about 2 ft. from the ends. Space the spokes with equal
divisions and cover the outer 2 ft. of the ends with boards, as
shown in the plan sketch on the right hand end of the drawing. The
boards may be nailed or bolted. If bolted and the wires made in a
loop at the hooks, the swing can easily be taken apart and changed
from one place to another.
--Contributed by A. O. Graham, Fort Worth, Tex.



** Home-Made Arc Lamp [132]

The frame of the lamp is made from bar metal 3/4 in. wide and 1/8
in. thick, bent and welded to make a continuous loop in the shape
as shown at G in the sketch. This frame should be about 10-1/2 in.
long with the upper or wider part 4 in. long, and the lower part
6-1/2 in. long. The width should be about 5-1/4 in. at

[Illustration: Arc Lamp]

the top and 4 in. at the bottom. A cross bar, L, made of the same
material, is fitted into the off-set in the frame and riveted.
Holes are drilled through the frame and brass bushings, H and J,
are fitted for bearings to receive the adjusting brass rod, B,
which should be 1/4 in. in diameter. A brass curtain rod can be
used for the rod B, and on its lower end a socket, P, is soldered.

A piece of brass 2 in. long, 1/2 in. wide and 1/8 in. thick is
used for the armature, A, to be operated by the magnet coil, C.
The coil, C, is made in the usual manner by wrapping No. 14
cotton-covered magnet wire on a wooden spool that has a soft iron
core. The spool is about 2-1/2 in. long. The armature, A, is
drilled, making a hole just a little larger than the rod, B, and
is adjusted in place by two set screws, D and E. A soft piece of
iron, F, is fastened to the opposite end of the armature with a
screw, which should be placed directly under the end of the coil's
core. This end of the armature may be kept from swinging around by
placing it between a U-shaped piece of brass fastened to the cross
piece L. At the bottom end of the frame, and directly centering
the holes H and J, a hole is drilled to receive a hard rubber
bushing, R, for insulating the brass ferrule, S, that holds the
lower carbon.

One connection is made from the main to the upper binding-post,
which is in turn connected to one terminal of the coil, C, the
other coil terminal being attached to the frame. The other main
connection is made to the lower binding-post, which is also
connected to the brass ferrule, S, by soldering. The two
binding-posts are insulated from the frame the same as the ferrule
S. When using on a 110-volt circuit there must be some resistance
in connection, which may be had by using German silver wire, or a
water rheostat heretofore described.
--Contributed by Arthur D. Bradlev. Randolph, Mass.



** Irrigation [132]

The Mexican government has appropriated $25,000,000 for irrigation
work.



** How to Hang Your Hat on a Lead Pencil [133]

Take a smooth hexagon lead pencil, one without either rubber or
metal end, and place it against a door or window casing; then with
a firm, heavy pressure slide the pencil some 3 or 4 in. and it
will stay as if glued to the casing. You may now hang your hat on
the end of the pencil.

When you slide the pencil along the casing, do it without any
apparent effort, and it will appear to your audience as though you
had hypnotized it. This is a very neat trick if performed right.
Figure 1 shows the pencil on the casing and Fig. 2 the hat hanging
on it.

[Illustration: Pencil Trick]



** Tying a Knot for Footballs [133]

One of the most prominent English football clubs kept the tying of
this knot on the rubber hose of their football a secret and never
allowed all of its members to know how it was tied. This tie can
be used on grain sacks, and in numerous other like instances. Make
one loop in the cord and then another exactly the same way, as

[Illustration: A Secure Knot]

shown in Fig. 1, placing the end of the cord under the first loop,
then pulling at each end of the cord as in Fig. 2.--A.E.J.



** Stove polish [133]

Stove polish consists of 2 parts graphite, 4 parts copperas and 2
parts bone black, mixed with water to form a paste.



** How to Give an Electric Shock While Shaking Hands [133]

There is nothing quite so startling as to receive an electric
shock unexpectedly and such a shock may be given to a friend while
shaking hands upon meeting. The shock produced is not harmful and
the apparatus can be carried in the pocket. It consists of a small
induction coil that can be constructed at home.

The core of the coil, A, Fig. 1, is constructed in the usual
manner, of small soft-iron wire to make a bundle about 3/16 in. in
diameter and 2 in. long. The coil ends are made from cardboard,
about 1 in. in diameter, with a 3/16-in. hole in the center. The
hole

[Illustration: Details of Induction Coil]

should be cut as shown in Fig. 2, so as to have four small pieces
that can be bent out, leaving the projections as shown. After
wrapping three or four turns of paper around the bundle of wires
the cardboard ends are put on with the projections inside, so the
coils of wire will hold them in place. About 70 turns of No. 24
gauge double covered magnet wire is first placed on the core, for
the primary, and then 1,500 turns of No. 32 or 34 gauge
double-covered wire is wrapped on top of the primary, for the
secondary. Sufficient length of wire must be left outside at each
end of both windings to make connections. The vibrator B, Fig. 1,
and the support C are made from thin spring steel, about 1/8 in.
wide, bent as shown and securely fastened to the cardboard end of
the coil. The armature is made from a soft piece of iron, about
3/16 in. in diameter and 1/16 in. thick, which is soldered to the
end of the vibrator directly opposite the end of the core. A small
screw is fitted in the end of the support, C, for adjustment,
which should be tipped with platinum and also a small piece of
platinum placed where the screw will touch the vibrator, B.

One of the primary wires is connected to the screw support. The
vibrator, is connected to a flash lamp battery, D. The other
primary wire is connected to a switch, S, which in turn is
connected to the other terminal of the battery. The switch, S, may
be made from a 3/8-in. cork with the wires put through about 3/16
in. apart and allow them to project about 1/2 in. The plate E is
cut about 1/2 in. square from a piece of copper and is fastened to
the heel of one shoe and connected with a wire from the secondary
coil which must be concealed inside of the trouser leg. The other
secondary wire is connected through the coat sleeve to a finger
ring, F. The vibrator screw must be properly adjusted. When the
vibrator is not working the armature should be about 1/16 in. from
the core and directly opposite.

The coil when complete will be about 2-1/2 in. long and 1 in. in
diameter. The coil can be placed in an old box that has been used
for talcum powder or shaving stick. The space around the coil in
the box can be filled with paper to keep it tight.

The coil and battery are carried in the pockets and the cork
button put in the outside coat pocket, where it can be pressed
without attracting attention.



** Experiment with Heat [134]

[Illustration: Heat Experiment]

Place a small piece of paper, lighted, in an ordinary water glass.
While the paper is burning turn the glass over and set into a
saucer previously filled with water. The water will rapidly rise
in the glass, as shown in the sketch.



** How to Attach a Combination Trunk Lock [134]

[Illustration: Trunk Lock]

A small combination lock for chests can be purchased for a small
sum of money and attached to a trunk cover after first removing
the old lock as shown in Fig. 1. It is necessary to add 1/2-in. to
the thickness of the trunk lid or cover. This may be done by
placing a brass plate 1/8-in. thick on the outside and a board
3/8-in. thick on the inside. The lock, brass plate, board and
trunk cover are all securely riveted together. The support for the
dial is soldered to the brass plate.

The hasp, if that be the name for the double toothed arrangement
that catches into the lock, was to be secured by only three brass
screws, which seemed to be insufficient, says a correspondent of
the Metal Worker; therefore a piece of heavy tin was formed over
the front of the trunk, which is only 3/8-in. board, the hasp
tinned and soldered to the back of the now U-shaped tin, and the
tin placed over the board and all fastened in position. The tin is
4 in. wide, 16 in. long and when placed over the board, it laps
down about 8 in. between the boards, and the same distance inside
of the new board, as shown by the heavy line in the cross section,
Fig. 1. Wrought nails are used which pass twice through the tin
and both boards, and then well clinched. The three screws were
then put in the hasp.

The knob on the dial extends out too far, which may be filed off
and two holes substituted, as shown, with which to operate the
dial. An old key is filed down in the shape shown in Fig. 2 to fit
the two holes.

As the dial is convex it will need protection to prevent injury by
rough handling. A leather shield may be used for this purpose,
which is cut with two holes, one for the key and the other to
permit the operator to observe the numbers on the dial. The shield
answers a further purpose of preventing any bystander from noting
the numbers on the dial.



** AN ELECTRIC ILLUSION BOX [135]

The accompanying engravings show a most interesting form of
electrically operated illusion consisting of a box divided
diagonally and each division alternately lighted with an electric
lamp. By means of an automatic thermostat arranged in the lamp
circuit causing the lamps to light successively, an aquarium
apparently without fish one moment is in the next instant swarming
with live gold fish; an empty vase viewed through the opening in
the box suddenly is filled with flowers, or an empty cigar box is
seen and immediately is filled with cigars.

These electric magic boxes as shown are made of metal and oxidized
copper finished, but for ordinary use they can be made of wood in
the same shape and size. The upper magic boxes as are shown in the
engraving are about 12 in. square and 8-1/2 in. high for parlor
use and the lower boxes are 18 in. square and 10-1/2 in. high for
use in window displays. There is a partition arranged diagonally
in the box as shown in the plan view, which completely divides the
box into two parts. One-half the partition is fitted with a plain,
clear glass as shown. The partition and interior of the box are
rendered non-reflecting by painting with a dull, not shiny, black
color. When making of wood, a door must be provided on the side or
rear to make changes of exhibits. If the box is made large enough,
or in the larger size mentioned, openings may be made in the
bottom for this purpose, and also used in case of performing the
magic trick of allowing two persons to place their

[Illustration: Construction of Magic Boxes]

heads in the box and change from one to the other.

The electric globes are inserted as shown at LL through the top of
the box, one in each division. When the rear part is illuminated,
any article arranged within that part will be visible to the
spectator looking into the box through the front opening, but when
the front part is illuminated, and the back left dark, any article
placed therein will be reflected in. the glass, which takes the
same position to the observer as the one in the rear. Thus a plain
aquarium is set in the rear part and one with swimming fish placed
in

[Illustration: Four Electric Magic Boxes Complete for Use]

the front, and with the proper illumination one is changed, as it
appears, into the other. When using as a window display, place the
goods in one part and the price in the other. Many other changes
can be made at the will of the operator.

Electric lamps may be controlled by various means to produce
different effects. Lamps may be connected in parallel and each
turned on or off by means of a hand-operated switch or the button
on the lamp socket, or if desired a hand-operated adjustable
resistance may be included in the circuit of each lamp for
gradually causing the object to fade away or reappear slowly.

Instead of changing the current operated by hand, this may be done
automatically by connecting the lamps in parallel on the lighting
circuit and each connected in series with a thermostatic switch
plug provided with a heating coil which operates to automatically
open and close the circuit through the respective lamp.

When there is no electric current available, matches or candles
may be used and inserted through the holes H, as shown in the
sketch, alternately.



** Replace Dry Putty [136]

Painting over putty that has not become dry will cause scaling or
cracking around the edges of the putty.



** Photo Print Washing Tank [136]

The accompanying sketch shows a simple form of a print washing
tank that tips from side to side by the weight of the water. For
prints 4 by 5 and 5 by 7-in. a tank 2 ft. long and 1 ft. wide will
be about the right size. This tank is then divided with a
partition placed exactly in the center. This partition should
extend 3 or 4 in. above the top of the tank. The partition may
also extend below the tank about 1-1/2 in., or a piece of this
width put on the bottom, as shown at A in the sketch.

[Illustration: Keeps Prints Constantly Moving]

A row of holes about 1/2 in. in diameter is bored through each end
of the tank, as shown at B. These holes will allow the water to
spill out while the opposite side is filling. The tank may be made
from 1/2-in. material and when completed as shown, lined with oil
cloth to make it watertight. The tank is placed with the partition
directly under a water tap and the flow of water will cause it to
tip from time to time, keeping the prints constantly moving about
in the water.



** Home-Made Soldering Clamps [137]

Take a cotter pin and bend it over a small rod to bring the points
together, as shown in the sketch. This will make a spring clamp
that is opened to slip over the articles to be clamped together by
inserting a scratch awl or scriber between the legs at the bowed
portion. To make a more positive clamp before bending the legs to
a bow, slip a short coil of wire over the pin, passing it down to
the ring end. Wire 1/32 in. in diameter wound over a wire slightly
larger in diameter than that of the cotter will do. In soldering,
smoke the legs well to avoid solder adhering to them. The clamp is
tightened by pushing up the coil ring toward the bow of the legs
and then twisting it like a nut, the coil being wound
right-handed, so that it will have a screw effect.

[Illustration: Clamp]



** A Telephone Experiment [137]

If the small apparatus, as shown in the accompanying sketch, is
attached to the under side of an ordinary dining table, it will,
if connected to a telephone circuit, set the table in vibration,
so that any number of people who put their ears flat upon the
table will hear the voice of a person speaking from a distance,
apparently coming out of the table, says the Model Engineer. A
small piece of wood, A, Fig. 1, is cut about 5 in. square, to the
center of which is attached a small piece of soft iron wire, such
as used for cores

[Illustration: Mechanical Table Talk]

of induction coils, about 4 in. long and bent in the form of a
hook at the lower end, as shown at B. This wire is attached to the
block of wood, A, as shown in Fig. 2. The end of the wire is
soldered to a small brass plate which is set in the block so it
will be level or flush with the top of the block and then fastened
with two screws. The block A is fastened to the under side of the
table with two screws. A small coil, C, is made by winding No. 24
silk or cotton covered wire around a small tube, either a piece of
glass, a short straw or a quill. The coil is made tapering as
shown without using wood ends. This coil is slipped over the wire
B previous to soldering it to the small brass plate. The ends of
the coil are connected to two binding-posts which are fastened to
the block A. A small lead weight weighing 2 or 3 oz. is hung on
the hook made in the lower end of the wire B.

When all connections are made, as shown in Fig. 1, and the block
fastened to the under side of the table, the apparatus is ready
for use, and has only to be connected to an ordinary telephone
transmitter and batteries as shown. The apparatus will work to a
certain extent even if the weight is removed, though not so clear.



** Wax Wood Screws [137]

Some workmen use tallow on lag or wood screws. Try beeswax for
this purpose. It is much cleaner to use and is just as good if not
better.



** How to Make an Induction Coil [138]

A small shocking coil, suitable for medical purposes, may be
constructed of materials found in nearly every amateur mechanic's
collection of odds and ends. The core, A, Fig. 1, is a piece of
round soft iron rod about 1/4 in. in diameter and about 4 in.
long. A strip of stiff paper about 3/4 in. wide is covered with
glue and wrapped around one end of the core, as shown at B, until
the diameter is about 3/8 in. The portion of the core remaining
uncovered is then wrapped with a piece of paper about 4 in. wide.
No glue is used on this piece, as it is removed later to form the
space, C, after the paper shell, D, has been wound upon it. This
paper shell is made of stiff paper and glue the same as B and is
made about 3/64 in. thick. Two pieces of hardwood, EE, 1-3/4 in.
square and about 5/16 in. thick, are drilled in the center and
glued on the ends of the paper shell as shown.

The primary winding consists of 4 or 5 layers of No. 18 or 20
single cotton-covered magnet wire, the ends of which may be passed
through small holes in the wooden ends. If a drill small enough is
not available, the holes may be made with a hot knitting needle or
a piece of wire heated to redness. After the primary coil is wound
it should be thoroughly insulated before winding the secondary.
This may be done by wrapping with 4 or 5 thicknesses of paper.

The secondary coil should be wound with single covered wire,
preferably silk-covered, although cotton will do. The more turns
there are on the secondary the higher the voltage will be, so the
wire used must be fine. Number 32 to 36 will give good results,
the latter giving more voltage but less amperage. Each layer of
the secondary winding should be insulated from the others by a
piece of thin paraffined paper wrapped over each layer as it is
finished. It is well not to wind to the extreme ends of the paper
insulations, but to leave a space of about 1/8-in. at each end of
the winding to prevent the wires of one layer slipping over the
ends of the paraffin

[Illustration: Induction Coil]

paper and coming in contact with the layer beneath, thus causing a
short circuit. The secondary winding should have at least a dozen
layers and should be carefully wound to prevent short circuiting.

In order to reduce the strength of the current a piece of brass
tubing, F, is pushed into the space, C, surrounding the core, or
if no brass tubing of the required size is on hand, roll a paper
tube, cover with 4 or 5 thicknesses of tinfoil and then wrap with
more paper, using glue to hold the tinfoil in place and to keep
the tube from unwinding. When the tube is pushed all the way in,
the current produced

[Illustration: Induction Coil]

will be almost unnoticeable, but when it is withdrawn the current
will be so strong that a person cannot let go the handles until
the coil is shut off. After the secondary coil is wound it should
be covered with stiff paper, and the whole coil, including the
wood ends, should then be enameled black.

It is then ready to be mounted on a wooden base as shown in Fig.
2. The secondary terminals are connected to the binding-posts, AA,
which may be fastened on the base if desired. One wire from the
primary is connected with the binding-post, B, and the other is
connected with the armature, D, which may be taken from an old
electric bell. The contact screw, E, also from an electric bell,
is connected to the binding-post, C. The contact spring, F, should
be bent against and soldered to the armature in order to make the
vibrations more rapid.

If a false bottom is used on the base, all the wiring may be
concealed, which adds greatly to the appearance and if desired a
small switch may be added. The handles, which may be old bicycle
pumps or electric light carbons, are connected to the
binding-posts, AA, by means of wires about 3 or 4 ft. long. This
coil when operating with the tube pulled all the way out and
connected to a single dry cell will give a current stronger than
most persons can stand.



** Home-Made Toaster [139]

Each outside frame of the toaster is made from one piece of wire
30 in. long. These are bent in a perfect square making each side
7-in. long. This will allow 1 in. on each end for tying by
twisting the ends together. The first two wires inside and on each
side of each frame are 8 in. long. Eight wires will be required
for this purpose and as they are 8 in. long 1/2 in. is allowed on
each end for a bend around the outside frame, as shown in the
sketch. The two middle wires are extensions of the handles. Each
of these wires are made from a piece about 26 in. long and bent in
the shape of a U. The ends of the wire are bent around the frame
in the same manner

[Illustration: Toaster]

as the other wires. This will leave the handle laying across the
other side of the frame. The frame is fastened to the handle on
this side by giving the handle one turn around the frame. The
inside edges of the frame are now tied together with a small ring
of wire which is loose enough to allow each half to swing freely.
--C. D. M.



** Home-Made Shocking Machine [139]

An ordinary electric bell may be connected up in such a way as to
produce the same results as an expensive

[Illustration: Inexpensive and Effectual]

shocking machine. The connections are made from the batteries to
the bell in the usual manner. Two other wires are then connected,
one to the binding-post of the bell that is not insulated from the
frame and the other to the adjusting screw on the make and break
contact of the bell as shown in the sketch. The other ends of the
wires are connected each to a common table knife. This will give
quite a good shock and a much larger one can be had by placing one
knife in a basin of water and while holding the other knife in one
hand, dipping the fingers of the other hand in the water.
--Contributed by D. Foster Hall.



** Mahogany Wood Putty [139]

Mix venetian red with quite thick arabic muscilage, making it into
a putty, and press this well into the cracks of mahogany before
finishing. The putty should be colored to suit the finish of the
wood, says the Master Painter, by adding such dry color to the gum
as will give the best result.



** How to Make a Thermoelectric Battery [140]
By Arthur E. Joerin

A novel way of producing an electric current by means of hot and
cold water, heat from a match or alcohol

[Illustration: Details of Battery]

lamp, is obtained from a device constructed as shown in the
sketch. Take two hardwood boards, marble, or slate plates, about 8
or 10 in. long, place them together, as in Fig. 1, and mark and
drill about 500 holes. These two pieces should be separated about
8 in. and fastened with boards across the ends, as shown in Fig.
2.

Take soft copper wire, not smaller than No. 18 gauge, and cut in
lengths to pass through the holes in the two boards, leaving
sufficient end to make a tie. It will require about 70 ft. of wire
to fill one-half the number of holes. Also, cut the same number of
lengths from the same gauge galvanized-iron wire to fill the
remaining holes. The wires are put through the holes in the boards
alternately, that is: begin with copper, the next hole with iron,
the next copper, the next iron, and so on, twisting the ends
together as shown in Fig. 3. The connections, when complete,
should be copper for the first and iron for the last wire.

When the whole apparatus is thus strung, the connections, which
must be twisted, can be soldered. Connect one copper wire to the
bell and the other terminal, which must be an iron wire, to the
other post of the bell. The apparatus is then short-circuited, yet
there is no current in the instrument until a lighted match, or,
better still, the flame of an alcohol lamp is placed at one end
only.

Best results are obtained by putting ice or cold water on one side
and a flame on the other. The experimenter may also place the
whole apparatus under sink faucets with the hot water turned on at
one terminal and the cold water at the other. The greater the
difference of temperature in the two terminals, the more current
will be obtained.

Very interesting experiments may thus be performed, and these may
lead to the solving of the great thermoelectric problem.



** How to Make a Hygrometer [140]

Mount a wire on a board which is used for a base and should be 3/8
by 4 by 8 in., as shown in the sketch. A piece of catgut--a string
used on a violin will do--is suspended from the bent end of the
wire. A hand or pointer is cut from a piece of tin and secured to
the catgut string about 1/2 in. from the base. A small piece of
wood and some glue will fasten the pointer to the string. The
scale is

[Illustration: Simple Hygrometer]

marked on a piece of cardboard, which is fastened to the base and
protected with a piece of glass.
--Contributed by J. Thos. Rhamstine.



** Softening Leather in Gloves and Boots [140]

The leather in high-top boots and gauntlet gloves may be softened
and made waterproof by the use of plain mutton tallow. Apply hot
and rub in well with the fingers.



** How to Make a Mission Library Table [141]

The mission library table, the drawings for which are here given,
has been found well proportioned and of pleasing appearance. It
can be made of any of the several furniture woods in common use,
such as selected, quarter-sawed white oak which will be found
exceptionally pleasing in the effect produced.

If a planing mill is at hand the stock can be ordered in such a
way as to avoid the hard work of planing and sandpapering. Of
course if mill-planed stock cannot be had, the following
dimensions must be enlarged slightly to allow for "squaring up the
rough."

For the top, order 1 piece 1-1/8 in. thick, 34 in. wide and 46 in.
long. Have it S-4-S (surface on four sides) and "squared" to
length. Also, specify that it be sandpapered on the top surface,
the edges and ends.

For the shelf, order 1 piece 7/8 in. thick, 22 in. wide and 42 in.
long, with the four sides surfaced, squared and sandpapered the
same as for the top.

For the side rails, order 2 pieces 7/8 in. thick, 6 in. wide and
37 in. long, S-4-S and sanded on one side. For the end rails, 2
pieces 7/8 in. thick, 6 in. wide and 25 in. long. Other
specifications as for the side rails.

For the stretchers, into which the shelf tenons enter, 2 pieces
1-1/8 in. thick,

[Illustration: This Picture Is from a Photograph of the Mission
Table Described]

3-3/4 in. wide and 25 in. long, surfaced and sanded on four sides.
For the slats, 10 pieces 5/88 in. thick, 1-1/2 in. wide and 17 in.
long, surfaced and sanded on four sides. For the keys, 4 pieces
3/4 in. thick, 1-1/4 in. wide and 2-7/8 in. long, S-4-S. This
width is a little wide; it will allow the key to be shaped as
desired.

The drawings obviate any necessity for going into detail in the

[Illustration: Table Details]

description. Fig. 1 gives an assembly drawing showing the relation
of the parts. Fig. 2 gives the detail of an end. The tenons for
the side rails are laid off and the mortises placed in the post as
are those on the end. Care must, be taken, however, not to cut any
mortises on the post, below, as was done in cutting the stretcher
mortises on the ends of the table. A good plan is to set the posts
upright in the positions they are to occupy relative to one
another and mark with pencil the approximate positions of the
mortises. The legs can then be laid flat and the mortises
accurately marked out with a fair degree of assurance that they
will not be cut where they are not wanted and that the legs shall
"pair" properly when effort is made to assemble the parts of the
table.

The table ends should be glued up first and the glue allowed to
harden, after which the tenons of the shelf may be inserted and
the side rails placed.

There is a reason for the shape, size and location of each tenon
or mortise. For illustration, the shape of the tenon on the top
rails permits the surface of the rail to extend almost flush with
the surface of the post at the same time permitting the mortise in
the post to be kept away from that surface. Again, the shape of
the ends of the slats is such that, though they may vary slightly
in length, the fitting of the joints will not be affected. Care
must be taken in cutting the mortises to keep their sides clean
and sharp and to size.

In making the mortises for the keyed tenons, the length of mortise
must be slightly in excess of the width of the tenon--about
1/8-in. of play to each side of each tenon. With a shelf of the
width specified for this table, if such allowance is not made so
that the tenons may move sideways, the shrinkage would split the
shelf.

In cutting across the ends of the shelf, between the tenons, leave
a hole in the waste so that the turning saw or compass saw can be
inserted. Saw within one-sixteenth of the line, after which this
margin may be removed with chisel and mallet.

In Fig. 3 is shown two views of the keyed tenon and the key. The
mortise for the key is to be placed in the middle of the tenon. It
will be noted that this mortise is laid out 1-1/16 in. from the
shoulder of the tenon while the stretcher is 1-1/8 in. thick. This
is to insure the key's pulling the shelf tightly against the side
of the stretcher.

Keys may be made in a variety of shapes. The one shown is simple
and structurally good. Whatever shape is used, the important thing
to keep in mind is that the size of the key and the slant of its
forward surface where it passes through the tenon must be kept the
same as the mortise made for it in the tenon.

The top is to be fastened to the rails by means either of wooden
buttons, Fig. 4, or small angle irons.

There are a bewildering number of mission finishes upon the
market. A very satisfactory one is obtained by applying a coat of
brown Flemish water stain, diluted by the addition of water in the
proportion of 2 parts water to 1 part stain. When this has dried,
sand with number 00 paper, being careful not to "cut through."
Next, apply a coat of dark brown filler; the directions for doing
this will be found upon the can in which the filler is bought. One
coat usually suffices. However, if an especially smooth surface is
desired a second coat may be applied in a similar manner.

After the filler has hardened, a very thin coat of shellac is to
be put on. When this has dried, it should be sanded lightly and
then one or two coats of wax should be properly applied and
polished. Directions for waxing are upon the cans in which the wax
is bought. A beautiful dull gloss so much sought by finishers of
modern furniture will be the result of carefully following these
directions.



** A Hanger for Trousers [143]

Secure two clothes pins of the metal spring kind for the clamps of
the hanger. The pins are fastened one to each end of a looped
galvanized wire. This wire should be about 6 in. long after a coil
is bent in the center as shown in the sketch. The diameter of the
wire should be about 1/8 in.

[Illustration: Hanger]



** How to Make an Adjustable Negative Washer [143]

The sketch herewith shows a washing box for negatives made from an
ordinary wooden box. As can be seen, the grooved partition, A, is
removable, and as several places are provided for

[Illustration: Washing Box]

its insertion, the tank can be made to accommodate anyone of
several sizes of plates, says Camera Craft. The other stationary
partition, B, which does not reach quite to the bottom of the
tank, is placed immediately next to the end of the tank, leaving a
channel between the two for the inflow of the wash water. A
narrow, thin strip, C, is fastened to the bottom of the tank to
keep the plates slightly raised, at the same time allowing a
clearer flow of the water from the bottom upwards to the
discharge.

The water enters the narrow partition at the end, flows under the
partitions B and A, then upward between and parallel to the
surface of the plates, escaping at the opposite end over the top
of the tank end, in which the upper part has been cut away for
that purpose. The depth of this cut, in the upper part of the tank
end, should allow the overflow to be a trifle higher than the
width of the largest size plate for which the tank is fitted.
Partition B being stationary, can be nailed in position
permanently, allowing the bottom edge to clear the bottom of the
tank the desired distance. Partition A being movable should have
attached to its bottom edge a couple of nails, D, or better still,
wooden pegs, which will keep it also above the bottom of the tank
at the desired height.

A coat of paraffin paint should be applied, and, just before it
sets perfectly hard, any rough spots trimmed down with a knife or
chisel and a second lighter coat applied. If the wood is very dry
and porous a preliminary coat of the paint should be applied and
allowed to soak into the pores. It is also well to apply a coat of
the paint to the joints at the corners and around the edge of the
bottom before nailing together.



** Turn-Down Shelf for a Small Space [144]

The average amateur photographer does not have very much space in
which to do his work. The kitchen is the room used ordinarily for
finishing the photographs. In many instances there will not be
space enough for any extra tables, and so a temporary place is
prepared from boxes or a chair on which to place the trays and
chemicals. Should there be space enough on one of the walls a
shelf can be made to hang down out of the way when not in use. A
shelf constructed on this order may be of any length to suit the
space or of such a length for the purpose intended. A heavy piece
of wood, about

[Illustration: Turn Down Shelf]

1-1/2 in. thick, and 4 to 6 in. wide, is first fastened to the
wall at the proper height with nails, or, much better, large
screws.

The shelf is cut and planed smooth from a board 12-in. wide and
about 1-in. thick. This board is fastened to the piece on the wall
with two hinges as shown in Fig. 1. A small cleat is nailed to the
outer and under edge of the board and in the middle as shown. This
is used to place a support under the outer edge of the shelf. The
support, A, Fig. 2, should be long enough to extend diagonally to
the floor or top of the baseboard from the inner edge of the cleat
when the shelf is up in its proper place. --L. L.



** Home-Made Electric Battery Massage [144]

A simple and cheap electric massage device can be made by using
three or

[Illustration: Electric Massage]

four cells of dry battery connected to two ordinary silver
tablespoons, as shown in the sketch. The handles of the spoons
should be insulated or the operator can wear either kid or rubber
gloves.



** How to Make Tint Lantern Slides [144]

Purchase some lantern slide plates and fix them in hypo without
exposing, in the usual manner, same as you would an exposed plate,
says the Moving Picture World. This leaves a thin, perfectly
transparent emulsion film on the glass, which will readily take
color. Mix a rather weak solution of clear aniline dye of the
desired color and dip the plate in it, wiping the plate side
clean. If not dark enough, dip again and again until desired tint
is attained, letting it dry between each dipping. A very light
blue tint slide will brighten a yellow film considerably, but the
tint must be very light, just a bare tint.



** A Bicycle Catamaran [145]

The accompanying photographs show a bicycle boat made to carry two
persons.

[Illustration: This Catamaran Carries Two People]

This boat is constructed by using two galvanized iron tubes 18 ft.
long and 12 in. in diameter, tapered at the front end down to
cast-iron points, and the rear end shaped to attach rudders. These
tubes are placed 26 in. apart, giving the boat an extreme width of
50 in.

The cylinders support a platform and on the rear end of this
platform is constructed a paddle wheel 52 in. in diameter with 16
spokes. On the end of each spoke is fastened a galvanized sheet
metal blade 6 in. wide and 8 in. long. A large guard placed over
the paddle wheel forms a seat for one person and a chair in front
on the platform provides a place for a second person.

The person in front helps to propel the boat with hand levers
which are connected with rods to sprocket wheels on each side of
the platform. The occupant of the rear seat contributes his part
of the power with his feet on pedals of the shaft that carries the
sprocket wheels. This shaft and sprocket wheels drive the paddle
wheel by side chains of the bicycle kind. The boat is steered from
the rear seat by ropes attached to double rudders. This boat will
run at considerable speed and is very steady in rough water as it
goes directly through large waves instead of going over them.
--Contributed by Ernest Schoedsack, Council Bluffs, Iowa.



** How to Make a Lead Pencil Rheostat [145]

Take an ordinary lead pencil and cut seven notches at equal
intervals on the pencil down to and around the lead, leaving it
bare. A seven-point switch is constructed on a board of suitable
size making the points by using screws that will go through the
board. A small piece of tin or brass will do for a switch and is
fastened as shown. The connections are made on the back side of
the board as shown by the dotted lines. This will reduce 40 to 50
volts down to 5 or 10 volts for short lengths

[Illustration: Simple Rheostat]

of time.
--Contributed by Roy Newby, San Jose, Cal.



** Homemade Shoe Rack [146]

The accompanying sketch explains how a boy can make his own shoe
rack that can be placed on the wall in

[Illustration: Shoe Rack]

the clothes closet. Figure 1 shows the construction of the bottom
to permit the dirt to fall through. Two boards, 9 in. wide and
about 3 ft. long, with six partitions between, as shown, will make
pockets about 6 in. long. The width of the pockets at the bottom
is 2 in. and at the top 5 in.
--Contributed by Guy H. Harvey, Mill Valley, Cal.



** How to Waterproof Canvas [146]

The method used by the British navy yards for waterproofing and
painting canvas so it will not become stiff and cracked is as
follows: One ounce of yellow soap and 1/2 pt. of hot water are
mixed with every 7 lb. of paint to be used. The mixture is applied
to the canvas with a brush. This is allowed to dry for two days
and then a coat of the same paint, without the soap, is laid on.
When this last coat is dry the canvas may be painted any color
desired. After three days of drying the canvas may be folded up
without sticking together, and is, of course, waterproof. Canvas
waterproofed in this manner makes an excellent covering for
portable canoes and canvas boats. The color mixture for the soap
and second application is made from 1 lb. of lampblack and 6 lb.
of yellow ocher, both in oil; the finish coat may be any color
desired. When no paint is to be used on the canvas it may be
waterproofed with a mixture made from soft soap dissolved in hot
water, and a solution of iron sulphate added. Iron sulphate, or
ferrous sulphate, is the green vitriol. The vitriol combines with
the potash of the soap, and the iron oxide is precipitated with
the fatty acid as insoluble iron soap. This precipitate is then
washed, dried and mixed with linseed oil.



** Building a House in a Tree Top [146]

The accompanying photograph shows a small house built in a tree
top 20 ft. from the ground. The house is

[Illustration: Lofty Sentry Box for Guarding Watermelon Patch]

5 ft. wide, 5 ft. 1 in. long, and 6 ft. 6 in. high. A small
platform, 2 ft. wide, is built on the front. Three windows are
provided, one for each side, and a door in front. The entrance is
made through a trap door in the floor of the house. This house was
constructed by a boy 14 years old and made for the purpose of
watching over a melon patch.
--Contributed by Mack Wilson, Columbus, O.



** How to Make a Lamp Stand and Shade [147]

A library light stand of pleasing design and easy construction is
made as follows: Square up a piece of white oak so that it shall
have a width and thickness of 1-3/4 in. with a length of 13 in.
Square up two pieces of the same kind of material to the same
width and thickness, but with a length of 12 in. each. Square up
two pieces to a width and length of 3 in. each with a thickness of
1-1/8 in.

If a planing mill is near, time and patience will be saved by
ordering one piece 1-3/4 in. square and 40 in. long, two pieces
1-1/8 in. thick and 3 in. square, all planed and sandpapered on
all surfaces. The long piece can then be cut at home to the
lengths specified above.

The 13-in. piece is for the upright and should have a 1/2-in. hole
bored the full length through the center. If the bit is not long
enough to reach entirely through, bore from each end, then use a
red-hot iron to finish. This hole is for the electric wire or gas
pipe if gas is used.

The two pieces for the base are alike except the groove of one is
cut from the top and of the other from the under side, as shown.
Shape the under sides first. This can best be done by placing the
two pieces in a vise, under sides together, and boring two holes
with a 1-in. bit. The center of each hole will be 2-1/2 in. from
either end and in the crack between the pieces. The pieces can
then be taken out, lines gauged on each side of each, and the wood
between the holes removed with turning saw and scraper steel.

The width of the grooves must be determined by laying one piece
upon the other; a trysquare should be used to square the lines
across the pieces, however, gauge for depth, gauging both pieces
from their top surfaces. Chisel out the grooves and round off the
corners as shown in the sketch, using a 3/4-in. radius.

These parts may be put together and fastened to the upright by
means of two long screws from the under side, placed to either
side of the 1/2-in. hole. This hole must be continued through the
pieces forming the base.

The braces are easiest made by taking the two pieces which were
planed to 1-1/8 in. thick and 3 in. square and drawing a diagonal
on each. Find the middle of this diagonal by drawing the central
portion of the other diagonal; at this point place the spur of the
bit and bore a 1-in. hole in each block.

Saw the two blocks apart, sawing

[Illustration: Details of Construction of Library Lamp Stand]

along a diagonal of each. Plane the surfaces on the saw cut smooth
and sandpaper the curve made by the bit. Fasten the braces in
place by means of roundhead blued screws.

To make a shade such as is shown in the illustration is rather
difficult. The shade is made of wood glued up and has art glass
fitted in rabbets cut on the inner edges. Such shades can be
purchased ready to attach. The sketch shows one method of
attaching. Four small pieces of strap iron are bent to the shape
shown and fastened to the four sides of the upright. Electric
globes--two, three or four may be attached as shown.

The kind of wood finish for the stand will depend upon the finish
on the wooden shade, if shade is purchased. Brown Flemish is
obtained by first staining the wood with Flemish water stain
diluted by the addition of two parts water to one part stain. When
this is dry, sandpaper the "whiskers" which were raised by the
water and fill with a medium dark filler. Directions will be found
on the filler cans. When the filler has hardened, apply two coats
of wax.

The metal shade as shown in the sketch is a "layout" for a copper
or brass shade of a size suitable for this particular lamp. Such
shades are frequently made from one piece of sheet metal and
designs are pierced in them as suggested in the "layout." This
piercing is done by driving the point of a nail through the metal
from the under side before the parts are soldered or riveted
together. If the parts are to be riveted, enough additional metal
must be left on the last panel to allow for a lap. No lap is
needed when joints are soldered.

A better way, and one which will permit the use of heavier metal,
is to cut each side of the shade separately and fasten them
together by riveting a piece of metal over each joint. The shape
of this piece can be made so as to accentuate the rivet heads and
thus give a pleasing effect.

For art-glass the metal panels are

[Illustration: The Completed Lamp]

cut out, the glass is inserted from the under side and held in
place by small clips soldered to the frame of the shade. Pleasing
effects are obtained by using one kind of metal, as brass, and
reinforcing and riveting with another metal, such as copper.

[Illustration: METAL SHADE--Construction of Shade]



** Illuminating a Watch Dial at Night [149]

This picture shows a watch holder, with a device to receive an
ordinary electric pocket lamp and battery. The battery is set in a
bracket under which a reflector extends downward to throw the
light on the dial of the watch and to protect the eyes from the
direct light. The entire stand and bracket are made from sheet
metal. The base is formed to make a tray to hold pins and collar
buttons. It is not necessary to seek in the darkness for a push
button or switch, as in ordinary devices, but a light pressure
with the palm of the hand will make the lamp glow.

[Illustration: Lamp]



** Home-Made Photographic Copying Stand [149]

The difficulties of bad lighting on small articles can be entirely
avoided by the use of a suitable support for the camera, the
object and the background.

[Illustration: Secures Good Light on Small Objects]

For illustrations it is often an advantage to show an object with
a perfectly plain background and no deep shadows. When using the
stand as illustrated this is a very simple matter. Figure 1 shows
the side, and Fig. 2 the front view of this stand. The stand is
very easily constructed from pipe and pipe fittings. The main pipe
of the stand will need to be of proper length to suit the focus of
your camera. This can be determined by finding the length from the
lens to the object after the bellows are extended to their full
length. The arms holding the glass, as shown in the sketch, should
be set at a point about the middle of the main tube. The cross
that holds the middle arms should be 3/4 in. one way and 1/2 in.
the other. This will allow for adjustment of the glass table. A
small set screw provided in the back of this cross will hold the
table in any position desired. The pipes and other connections are
all 1/2-in. and the lengths of the pipes are made suitable for the
size of the camera. When a small object is to be photographed it
is placed upon the glass table and the background fastened to the
board. In this manner small objects can be photographed without
any deep shadow on one side. The bottom cross and ells should be
corked so as to prevent any slipping and damage to the floor.



** Home-Made Pocket Lamp [149]

A simple and safe pocket lamp that will last for about 6 months
without extra expense can be made at home for a few cents.

Have your druggist take a strong vial of clear glass, or a pill
bottle with screw or cork top and put into it a piece of
phosphorus about the size of a pea and fill the bottle one-third
full of pure olive oil that has been heated for 15 minutes--but
not boiled. Cork tightly and the result will be a luminous light
in the upper portion of the bottle. If the light becomes dim,
uncork and recork again. The lamp will retain its brilliancy for
about 6 months. This makes a perfectly safe lamp to carry. These
lamps are used by watchmen of powder magazines. Care should be
exercised in handling the phosphorus, as it is very poisonous.



** How to Make a Tangent Galvanometer [150]

Secure a piece of wood 1/2 in. thick and cut out a ring with an
outside diameter of 10-1/2 in. and an inside diameter of 9 in. and
glue to each side two other rings 1/4 in. thick with the same
inside diameter as the first ring and 11 in. outside diameter,
thus forming a 1/4-in. channel in the circumference of the ring.
If a lathe is at hand this ring can be made from a solid piece and
the channel turned out. Cut another circular piece 11 in. in
diameter for a base. Make a hole in the center of this piece 1 in.
wide and 6-5/16 in. long, into which the ring first made should
fit so that its inner surface is just even with the upper surface
of the baseboard. The ring is held upright in the hole by a small
strip screwed to the base as shown. All screws and brads that are
used must be of brass. The cutting of these circular pieces is not
so difficult if a band saw driven by power is used. They can be
cut by means of a key-hole saw if a band saw is not accessible.

Before mounting the ring on the base, the groove should be wound
with 8 turns of No. 16 double cotton-covered magnet wire. The two
ends may be tied together with a string to hold them temporarily.

Fasten two strips of wood 1/4-in. thick 5/8-in. wide and 11 in.
long across the sides of the ring with their upper edges passing
exactly through the center of the ring. An ordinary pocket
compass, about 1-1/4 in. in diameter, is fitted in these strips so
that the center of the needle or pointer will be exactly in the
center of the ring and its zero point mark at the half-way point
between the two strips. Put the ring in place on the base, as
shown in the sketch, and connect the two ends of the wire to two
binding-posts that are previously attached to the base. Coat the
entire surface with brown shellac. Any deviation from the
dimensions will cause errors in the results obtained by its use.

Remove all pieces of iron or steel and especially magnets in the
near vicinity of the instrument when in use. Place the
galvanometer on a level table and turn it until the needle,
pointing north and south, and swinging freely, lies exactly in the
plane of the coil, as shown in the cut. The needle then will point
to zero if the directions have been followed closely. Connect one

[Illustration: Tangent Galvanometer]

cell of battery to the instrument and allow the current to flow
through the coils. The needle of the compass will be deflected to
one side or the other, and will finally come to rest at a certain
angle-let us say 45 deg. The dimensions of the instrument are such
that when the deflection is 45 deg. the current flowing through
the coils upon the ring is 1/2 ampere. The ampere is the unit
chosen to designate the strength of the electric current. For
other angles the value of the current may be found from the
following table:

Angles Degrees  Current Amperes
    10              .088
    20              .182
    30              .289
    40              .420
    45              .500
    50              .600
    55              .715
    60              .865
    70             1.375

As the magnetic force that acts upon a magnet needle varies in
different places the values given for the current will not be true
in all parts of the country. The table gives correct values for
the immediate vicinity of Chicago and that part of the United
States lying east of Chicago, and north of the Ohio river. The
results given should be multiplied by 1.3 for places south of the
Ohio river and east of the Mississippi.



** Home-Made X-Ray Instrument [151]

Two cylinders, AA, are mounted on a base, B, and mirrors, CC, are
fitted at an angle of 45 deg. into these cylinders. Corresponding
mirrors, EE, are put in the base parallel with those in those
cylinders. An opening extends downward from D of each cylinder so
that light entering at one end of the

[Illustration: Details of X-Ray Machine]

cylinder is reflected down at right angles by the first mirror to
the second, from the second to the third, from the third to the
fourth which reflects the light to the eye. Thus the light never
passes through the cylinders and the observer does not see
through, but around any object inserted at X between the
cylinders.



** How to Make a a Non-Polarizing Battery [151]

Bichromate batteries are very expensive to maintain and dry cells
do not furnish enough amperage for some kinds of experimental
work. A cell of a battery that will run 10 hours with an output of
over 1 ampere can be made as follows: Secure a jar about 4 in. in
diameter and 8 in. high and place in the bottom of this jar the
lower half of a tin baking powder can, to which a wire has been
soldered for connections. Place in the can a mixture of 2 oz.
black oxide of copper, 1 oz. black oxide of manganese and some
iron filings.

Purchase a small crowfoot zinc and hang it about 1 in. above the
half can. Prepare a 10 per cent solution of caustic soda and fill
the jar within 1 in. of the top. Place on top the solution a thin
layer of kerosene or paraffin. The cell will only cost about 50
cents to make and 25 cents for each renewal. When renewing, always
remove the oil with a siphon.
--Contributed by Robert Canfield, University Park, Colo.



** A Home-Made Barometer [151]

Take 1/4 oz. of pulverized campor, 62 gr. of pulverized nitrate of
potassium, 31 gr. nitrate of ammonia and dissolve in 2 oz.
alcohol. Put the solution in a long, slender bottle, closed at the
top with a piece of bladder' containing a pinhole to admit air,
says Metal Worker. When rain is coming the solid particles will
tend gradually to mount, little crystals forming in the liquid,
which otherwise remains clear; if high winds are approaching the
liquid will become as if fermenting, while a film of solid
particles forms on the surface; during fair weather the liquid
will remain clear and the solid particles will rest at the bottom.



** Lock Lubricant [151]

A door lock may be lubricated by using some lead scraped from the
lead in a pencil and put in the lock. This may be done by putting
the scrapings on a piece of paper and blowing them into the lock
through the keyhole.



** Rust Proofing Bolts [151]

Where bolts are subject to rust, the threads should be painted
with pure white lead; then they will not rust fast.



** Painting Yellow Pine [151]

When painting yellow pine exposed to the weather add a little pine
tar with the priming coat.



** Revolving a Wheel with Boat Sails [152]

A novel windmill or revolving wheel can be made by placing a light
wheel so it will turn freely on the end

[Illustration: An Unusual Type of Windmill]

of a post, and placing four small sailing boats at equal points on
the rim of the wheel. It makes no difference which way the wind
blows, the wheel will revolve in one direction. In Fig. 1 the
direction of the wind is shown by the arrows, and how the sails
catch the wind and cause the wheel to revolve. Figure 2 shows how
the wheel will appear when complete. This device makes an
attractive advertising sign.



** A Floating Electromagnet [152]

A piece of iron placed in a coil of wire carrying a current of
electricity becomes an electromagnet. If such a coil and iron core
be made small enough they can be attached to a cork and the cork,
floating on a solution, will allow the magnet to point north and
south. The sketch shows how to make such an instrument. A coil of
insulated wire is wrapped around a small iron core, leaving a few
inches of each end free for connections. The insulation is removed

[Illustration: Floating Electromagnet]

from these ends and they are run through a piece of cork. Attach
to the wires, on the under side of the cork, a piece of zinc to
one end and a piece of copper to the other. The cork is then
floated on a solution of acid, with the zinc and copper hanging in
the solution. If zinc and copper are used, the solution is made
from water and blue vitriol. If zinc and carbon are used, the
solution is made from sal ammoniac and water.

The float will move about on the solution until the magnet iron
will point north and south. If two of them are floating on the
same solution, they will move about and finally arrange themselves
end to end with the coils and magnet cores pointing north and
south.
--Contributed by C. Lloyd Enos.



** A Fish Bait [152]

A very effective fish bait is made by inclosing a live minnow in a
short section of glass tube, which is filled with water and both
ends closed with corks. This is used in place of the spoon.



** Homemade Air Thermometer [152]

The illustration shows the complete thermometer. The water in the
glass tube is caused to rise and fall by the expansion and
contraction of the air in the tin box. A paper-fastener box, about
1-1/4 in.

[Illustration: Air Thermometer]

deep and 2 in. in diameter will serve very well for the box A.
Solder in the side of the box 1-in. piece of 1/4-in. brass tubing,
B, and then solder on the cover, C, so that the only escape for
the air is through the brass tube. Secure a piece of 1/4-in. glass
tubing - not shorter than 18 in.--and bend it as shown at D in the
sketch. Hold the part of the tube to be bent in the broad side of
a gas jet, and in a minute or two the tube will bend with its own
weight. Any angle can be given glass tubing in this way. Connect
the glass tube to B with a short piece of rubber hose, E. If the
hose is not a tight fit, bind with a short piece of fine copper
wire. The standard, F, is made from a piece of No. 10 wire about
10 in. long. To this standard solder the supporting wire, G--No.
14 wire will do. On one side bend the wire around the tube B, and
on the other around the glass tube, D.

The base, H, can be made of oak, stained and varnished. The bottom
of the box, A, is covered with lampblack so as to readily absorb
all heat that strikes the surface. The black should not be put on
until just before you paint the supports, cover and rim of the box
with gold or silver paint. Hold the bottom of the box to be
blackened over a little burning cotton saturated with turpentine.

The scale on the glass can be etched with hydrofluoric acid, or
made with a little black paint. The water can be put in with a
medicine dropper. This instrument will measure the amount of heat
given by a candle some 20 or 30 ft. away.
--Contributed by J. Thos. Rhamstine.



** Home-Made Battery Voltmeter [153]

Secure a piece of brass tube 3 in. long that has about 1/4-in.
hole. Put ends, A, 1-1/4 in. square and cut from heavy cardboard
on this tube. Make a hole in the center of each cardboard just
large enough to allow the brass tube to fit tight. Put on two or
three layers of stout paper around the brass tube and between the
cardboard ends. Wind evenly about 2 oz. of No. 26 cotton covered
magnet wire on the paper between the ends and leave about 2 in. of
wire on each end extending from the coil. Use a board 1/2- in.
thick, 3 in. wide and 6 in. long for the base and fasten the coil
to it, as shown in Fig. 1. Bore holes for binding-posts, B, one on
each side of the board, and connect the two wires from the coil to
them. At the other end of the board and in the center drive a wire
nail and attach a small spring, C, to it. The spring should be
about 1 in. long. Take a small piece of soft iron, D, 1/2- in.
long and just large enough to slip freely through the brass

[Illustration: Battery Voltmeter Construction]

tube and solder a piece of copper wire to it; the other end of the
copper wire being hooked to the spring, C. The copper wire must be
just long enough to allow the piece of iron, D, to hang part way
in the end of the coil and still hold the spring in place. A
circular piece of cardboard, E, is slipped over the spring to
where the spring joins the wire. This cardboard is to serve as the
pointer. A piece of paper 1-1/2 in. wide and 2-1/2 in. long is
glued to the board so that it will be directly under the cardboard
pointer and fit snugly up against the top of the coil.

The paper can be calibrated by connecting one cell of battery to
the binding-posts. The iron plunger, D, is drawn into the tube and
consequently the pointer, E, is drawn nearer to the coil. Make a
mark directly under the place where the pointer comes to rest. At
the place mark the number of volts the cell reads when connected
with a voltmeter. Do the same with two or three cells and mark
down the result on the scale. By dividing off the space between
these marks you may be able to obtain a surprisingly correct
reading when connected with the battery cells to be tested.
--Contributed by Edward M. Teasdale, Cuba, N. Y.



** How to Make a Folding Canvas Cot [154]

All the material required to make the cot as shown in Fig. 1
consists of wood 1-1/2 in. square of which two pieces are 6 ft.
long; two pieces 2 ft. 3 in. long; two pieces 2-1/2 ft. long; four
pieces 1-1/2 ft. long; four hinges; some sheet metal and 2-1/4 yd.
of 8-oz. canvas.

Make a rectangle of the two long pieces and the two 2-ft. 3-in.
pieces of wood as shown in Fig. 2, nailing well the corners
together and reinforcing with a strip of sheet metal as shown in
Fig. 3. The four pieces 1-1/2 ft. long are used for the legs, and
two of them are nailed to one of the pieces 2-1/2 ft. long, making
a support as shown in Fig. 5.

Make two of these--one for each end.

[Illustration: Details of Canvas Cot Construction]

The hinges are attached as shown in Fig. 5 and the whole support
is fastened just under the end pieces of the frame by hinges. Four
pieces of sheet metal are cut as shown in Fig. 4 and fastened to
the body of the frame with their lower ends hooking over pins
driven in each leg at the proper place. The canvas is stretched as
tight as possible over the two long side pieces and fastened on
the outside edge of each piece with large headed tacks. The legs
will fold up as shown by the dotted line and the cot can be stored
in a small space.
--Contributed by R. J. Smith, Milwaukee, Wis.



** How to Make a Small Geissler Tube [154]

At first this would seem to be a difficult piece of work, yet a
good and beautiful Geissler tube can be made at home in the
following manner:

Procure a glass tube about 3-1/2 ft. long having a hole through
its center about 1/8 or 1/4 in. in diameter, about 1 in. of No. 30
platinum wire and enough mercury to fill the tube and a small
bowl. About 1-1/2 lb. of mercury will be sufficient. The first
thing to do is to seal 1/2 in. of platinum wire in one end of the
tube. This is done by holding the end of the tube with the right
hand and taking hold of the tube with the left hand about 4 in.
from the right hand. Hold the tube in a flame of a bunsen burner
in such manner that the flame will strike the tube midway between
the hands, as shown in Fig. 1, and keep turning the tube so as to
get an even heat. When the glass becomes soft,

[Illustration: Construction of Geissler Tube]

remove the tube from the flame and quickly draw it out into a fine
thread. Break this thread off about 1/8 in. from the long part of
the tube and the end will appear as shown in Fig. 2. Take 1/2 in.
of the platinum wire and slip it through the fine hole made by
breaking the glass thread so that one-half of the wire will be
inside of the long tube. If the end of the tube is now placed in
the flame of the burner, the glass will adhere to the platinum
wire and the wire will thus be sealed in the tube. The finished
end will appear as shown in Fig. 3. This tube as described will be
8 in. long, although nearly any size could be made in the same
way.

Measure 8 in. from the sealed end and place the tube at that point
in the flame, holding in the left hand. At the same time take the
piece of glass that was broken off at the end in the first
operation and hold it in the flame with the right hand. When both
the tube and piece of glass are soft, touch the soft part of the
tube with the end of the glass and draw the tube out into a point
like that shown in Fig. 4. Break off the piece of glass, thus
leaving a. small aperture in the long tube. Seal the remaining 1/2
in. of platinum in this aperture in the same manner as before
being careful not to heat the tube too suddenly. The tube is now
ready for filling and the upper part will appear as shown in Fig.
5.

The air is expelled from the tube by filling with mercury. This
may be done by making a paper funnel and pouring the mercury
slowly into the tube through the funnel. When the tube is filled
to within 1/2 in. of the funnel remove the funnel and tap the side
of the tube gently in order to remove any small air bubbles that
may be clinging to the sides of the tube. The air bubbles will
rise and come to the top. The tube now must be filled completely,
expelling all the air. Place a finger over the end of the tube to
keep the mercury in and invert the tube and set the end in the
bowl of mercury. The mercury in the tube will sink until the level
will be at about 30 in., leaving 8 in. of vacuum at the top. The
next operation is to seal the tube at the half-way point between
the lower platinum wire and the mercury level.

As the lower end of the tube must be kept at all times in the bowl
of mercury until the tube is sealed, an assistant will be
necessary for this last operation. Have the assistant hold the
tube in the mercury at a slight angle, using care to always keep
the lower end in the mercury, while you hold the burner in the
left hand and allow the flame to strike the tube at the stated
point. The part of the tube above this point will gradually bend
over of its own weight as the glass softens. When it reaches the
angle of about 60 deg., Fig. 6, take hold of the tube with the
right hand still keeping the flame on the tube, and gradually draw
the softened portion out until it separates from the main tube.

The tube is now finished and when the platinum wires are attached
to the terminals of a spark coil a beautiful blue light will
appear in the tube with a dark space at the negative end or
cathode.
--Contributed by David A. Keys, Toronto, Can.



** Loosening Rusted Nuts [155]

Nuts that are rusted fast can often be loosened by giving a hard
turn in the tightening direction.



** Cleaning Greasy Stoves [155]

Greasy stoves may be cleaned with a strong solution of lye or
soda.



** How to Make a Take-Down Background Frame [156]

Many amateur photographers who desire to do portrait work at home
have left the subject alone for the want of a suitable background.
A frame such as is used by the professional is entirely out of the
question in most homes, says a correspondent of Camera Craft. The
frame as shown in the sketch was devised and its chief advantage
lies in the fact that when not in use it can be compactly tied
together and stored away in a closet.

Almost any wood may be used in constructing this frame, but yellow
pine is the best, as it is easily obtained and at the same time
very well suited for such work. All pieces are to be dressed on
all sides.

Two upright pieces are cut from 3/4 in. material 2 in. wide and 5
ft. 9 in. long and two blocks are fastened on the ends of each
that are to be used for the bottom, as shown in Fig. 1. These
blocks are each 2 by 6-in. and 1/4 in. thick. The base is made
from a piece 3/4 in. thick, 3 in. wide and 5 ft. 4 in. long. A
crosspiece 3/4-in. thick, 3 in. wide and 12 in. long, cut in the
shape shown in Fig. 2, is screwed on each end of the base with
3-in. wood screws, as shown in Fig. 3. Four blocks 1/4 in. thick,
1 in. wide and 3 in. long are nailed to the sides of the base
piece parallel with and at a distance of 2 in. from the end of
same. This forms a slot, Fig. 4, to receive the pieces nailed to
the ends of the uprights. To secure a rigid frame it is essential
that this, joint be accurately put together.

Procure a piece of thick tin or brass and make two pieces like the
pattern shown in Fig. 5, with each projection 3-in. long. The
width of the crosspiece is 1 in. and the single projection 3/4 in.
These are bent and nailed, one on each end of a piece of wood that
is 1/4 in. thick, 1 in. wide and 5 ft. long, as in Fig. 6. These
will form two pockets that will fit over the tops of the uprights.
The frame is put together as shown in Fig. 7. Any background that
will hang straight without need of being stretched can be hung on
this frame.

[Illustration: FIG.6 -- Details of Background Frame]



**  Home-Made Kite Reel [156]

This kite reel is constructed from two old pulleys and a few pipe
fittings. The large pulley is about 14 in. in diameter, on the
face of which are riveted flat strips of iron with extending arms.
These arms are reinforced by riveting smaller pieces from one to
the

[Illustration: Old Pulleys and Pipe Fittings]

other, which connects all arms together on both sides of the
wheel. Mounted on the shaft with the pulleys is a guide for the
kite wire or string. The photograph shows that this guide permits
of being moved entirely over the top of the reel. The smaller
pulley is attached to the shaft and used as a brake. The brake is
used only when running out the wire or string, first removing the
crank.



** Attaching Runners to a Bicycle for Winter Use [157]

Instead of storing away your bicycle for the winter, attach
runners and use it on the ice. The runners can be made from
1/4-in. by 1-in. iron and fastened to the bicycle frame as shown
in the sketch. The tire is removed from the rim of the rear wheel
and large screws turned into the rim, leaving the greater part of
the screw extending. Cut off the heads of the screws and file them
to a point. The rear runners should be set so the rim of the wheel
will be about 1/2 in. above the runner level.
--Contributed by C. R. Welsh, Manhattan, Kan.

[Illustration: Bicycle Fitted with Runners for Snow]



** A Paper That Makes Green Prints [157]

A coating for ordinary paper that is said to give green prints is
made with a two per cent solution of gelatine, says Photography,
and sensitized with the following solution:

    Potassium Bichromate  15 gr.
    Magnesium Sulphate    25 gr.
    Water                  1 oz.

This mixture is spread over the paper in the usual way and the
paper dried in the dark. Printing is carried rather far. The print
is washed, then surface dried or blotted off on a pad and laid
film upwards on a sheet of glass, and the following developer is
applied with a wad of cotton wool wrung out:

    Pyrocatechin  5 gr.
    Water         1 oz.

The picture assumes a rich green color when developed, and is then
washed for five or ten minutes and dried quickly by heat.



** Copies Made from Wax Molds by Electro-Deposition [157]

Fine copies of wax impressions can be made in the following
manner: Procure an ordinary tumbler and fill it with a strong
solution of sulphate of copper, which is made by dissolving two
cents' worth of blue vitriol in 1/2 pt. of water. After this is
done make a porous cell by rolling a piece of brown paper around a
stick and fastening the edge with sealing wax; also, fix a bottom
to the cell in the same way. Make a solution of one part of oil of
vitriol and 5 parts of water and pour this mixture into the porous
cell. Wind the end of a copper wire around the end of a piece of
zinc and place the zinc in the porous cell. Attach the other end
of the wire to the wax impression.

The wax impression is made by pouring melted beeswax on the
article you wish to reproduce and removing after the wax gets
cold. The wax mold then should be coated with black lead and
polished. This is done with a camel's hair brush. A fine copy can
be made on the wax impression after the battery has been running
about 12 hr.
--Contributed by Edward M. Treasdale.

[Illustration: Electro-Deposition]



** How to Make Skating Shoes [158]

Remove the clamp part, as shown in Fig. 1, from an ordinary clamp
skate. Drill holes in the top part of the skate

[Illustration: Skating Shoes]

for screws. Purchase a pair of high shoes with heavy soles and
fasten the skates to the soles with screws, as shown in Fig. 2.
When completed the skating shoes will have the appearance shown on
Fig. 3. These will make as good skating shoes as can be purchased,
and very much cheaper.
--Contributed by Wallace C. Newton, Leominster, Mass.



** How to Make a Self-Setting Rabbit Trap [158]

Secure a good-sized box, say, 1 ft. high, 1-1/2 ft. wide, and 3
ft. long; and to the bottom, about 10 in. from one end, fasten a
2-in. square piece, A, Fig. 1, extending the width of the box.
Place a 10-in. board sloping from the end of the box to the cleat
A. The swing door B, Fig. 1, is made as shown

[Illustration: Self-Setting Trap]

in Fig. 2, which represents the back side of the door. Sheet metal
or tin is cut to the proper size and tacked around the edge of the
hole. This prevents the animal from gnawing its way out, also
provides a way to make the hole of different sizes for squirrels
or other animals. The hole in the door should be about 2 in. wide
and 4 in. high for rabbits. The door is made to swing freely on
two large nails driven through the sides of the box. The hole in
the door being only large enough to admit a small portion of the
rabbit's head, the rabbit will push its way through to the bait,
causing the door to swing back and up, and it will close by its
own weight when the animal is inside. A small door is provided in
the other end to remove the animals caught.

The advantage of this trap is that where one animal is caught
others are liable to follow, and several rabbits will be trapped
at a time. Then, too, the rabbits are not harmed in any way as
they would be if caught in an ordinary trap.
--Contributed by H. F. Church, Alexandria, Va.



** How to Make an Atomizer [158]

Secure a good-sized test tube and fit it with a cork. Take two
glass tubes, with about 1/8-in. hole, and bend them as shown in
the sketch. This is done by heating them at the proper point over
a gas flame until they are soft. Two holes are bored through the
cork and the bent tubes inserted in them, as shown in the sketch,
so that one of the tubes will extend nearly to the bottom

[Illustration: Atomizer]

of the test tube and the other just projecting through the cork.
The spray tube may be made with a fine hole by first securing a
tube longer than necessary and heating it at the proper point and
drawing the tube out into a fine thread. The thread is broken off
at the proper place to make a small hole.



** Home-Made Kits for the Camera [159]

If you have a 5- by 7-in. camera and wish to use some 4- by 5-in.
plates, make a few simple kits to hold the smaller plates and fit
the larger holders, says Camera Craft. Take two pieces of
pasteboard, A and B, black surfaced if possible, and exactly 5 by
7 in. in size. The piece A will form the back of the kit and
should have an opening cut in the center 4 by 5 in. in size. Paste
a piece of strong black paper, C, over the under side of it to
keep the plate from falling through. Cut an opening in the other
piece, B, but cut it 1/4 in. shorter. This opening, being 1/8 in.
shorter at each end, will retain the plate in position and cut off
only that small amount of plate surface when the plate is exposed
in the

[Illustration: Camera Kit]

camera. Cut a piece of thin black cloth, D, 1 in. wide and 5 in.
long. Lay it down on a piece of newspaper and coat one side with
gum or mucilage. Stand the two pieces of 5 by 7 in. black cards on
end together so that they will be square and true and bind the
other ends with the strip of cloth so as to form a hinge. The two
cards form a thickness about equal to a thick glass plate, and go
in the holder in the same way. Lay one of these kits down against
the ground side of the focusing screen and draw a line around,
inside of the opening. This will be a guide as to just what will
be secured upon the smaller plate when the kits are used.



** How to Make a Miniature Stage [159]

A good smooth box, say 8 in. wide, 10 in. high and 12 in. long,
will serve the purpose for the main part of this small theater.
Out two rectangular holes, Fig. 1, one in each end and exactly
opposite each other. Place a screw eye about 1/2 in. from the edge
on each side of these openings. Fit an axle in the screw eyes and
fasten a spool to the middle of the axle. On one of the two spools
attach another smaller spool, Fig. 2, to be used as a driving
pulley. Cut out the front part of the box down to a level with the
top of the spools. Connect the spools with a belt made from tape
about 3/4 in. wide. On this belt fasten figures cut from heavy
paper and made in the form of people, automobiles, trolley cars,
horses and dogs. A painted scenery can be made in behind the
movable tape. The front part of the box may be draped with
curtains, making the appearance of the ordinary stage, as shown in
Fig. 3. A small motor will run the spools and drive the tape on
which the figures are attached.
--Contributed by William M. Crilly, Jr., Chicago.

[Illustration: Details of Stage]



** A Floating Compass Needle [160]

When a thoroughly dry and clean sewing needle is carefully placed
on the surface of water the needle will float even if the density
of steel is 7 or 8 times that of water. A sewing needle thus
floating upon water may be used as a compass, if it has previously
been magnetized. The needle will then point north and south, and
will maintain this position if the containing vessel is moved
about; if the needle is displaced by force it will return to its
position along the magnetic meridian as soon as the restraint is
removed.



** Home-Made Dog Cart [160]

The accompanying photograph shows a boy with his "dogmobile." The
photograph was taken when they were on a new pavement which had 2
in. of sand


Dog-Power Cart

left by the pavers and a grade of 6 per cent. The machine is
nothing more than a boy's rubber-tired wagon on which are mounted
a box for a seat and a wheel steering device extending above and
below the board of the wagon. The front wheels are guided by ropes
attached from each end of the axle and a few turns around the
lower end of the steering rod. A pair of shafts are attached to
the rear, into which the dog is harnessed.



** How to Make a Dry Battery Cell [160]

[Illustration: Dry Battery Cell]

Dry battery cells are composed of the same materials for the
poles, but instead of the liquid commonly used a paste is formed
by mixing sal ammoniac and other salts with water and packed in
the cell so it cannot spill.

A cell of this kind can easily be made, and to make it the proper
size a sheet of zinc 8-1/2 in. long and 6 in. wide will be
required. This zinc is rolled into a cylinder 2-1/2-in. in
diameter. This will allow for a lap of 5/8 in., which is tightly
soldered only on the outside of the seam. Close one end of the
cylinder by soldering a disk of zinc over it, making a watertight
receptacle. All soldering should be done on the outside and none
of the solder allowed to run on the inside of the seam. All seams
on the inside should be painted with asphaltum in order to cover
any particles of solder. Do not paint any surface, only the
joints. Secure three carbon rods 1/2- in. in diameter and 6 in.
long which are copper plated. Carbons used in arc lamps will do.
File the rods to remove the copper plate, leaving about 1/2-in. of
the plate at one end. Tie the three rods in a close bundle with
the copper-plated ends together and make a contact with each rod
by soldering a wire to the plated ends, allowing one end of the
wire to project about 2 in. for a connection. The plated ends of
the carbons should be covered with paraffin for about 1 in. This
is done by immersing them in a dish of smoking hot melted paraffin
until the pores are thoroughly saturated.

The salts for filling are 1/4 lb. zinc oxide, 1 lb. sal ammoniac,
3/4 lb. plaster of paris, 1/4 lb. chloride of zinc mixed into a
paste by adding 1/2 pt. of water. Form a 1/2-in. layer of paste in
the bottom of the cylinder and place the ends of the carbon rods
on this with their plated ends up. Hold the rods in the center of
the cylinder and put the paste in around the rods with a stick.
Pack the paste in, closely filling the cylinder to within 3/4 in.
of the top. This space at the top is filled with a mixture of 1/2
lb. of rosin and 2 oz. beeswax melted together. This wax seals the
cell and prevents any evaporation. Connection is made to the zinc
by soldering a wire to the outside of the cylinder.



** How to Paraffin Wire [161]

The following description of how to make an apparatus with which
to paraffin wire as needed makes clear a method of construction
that is simple and easy to put together in a. short time.

Secure a pan to be used for this purpose only; one that will hold
about 1 qt. The details of the construction are given in the
diagram, in which P is the pan; B is a base of 1 in. pine; S is
the spool of wire supported near one end of the base by nailing on
standards H and H; F is a spool, with narrow flanges, supported
near the bottom of the pan by the standards T and T. These may be
made of two short pieces of a roller fitted into the holes bored
in the base; A is a block of l-in. pine with a piece of leather
tacked on one side. Four nails should be driven in the base just
outside of the edge of the pan to keep it from sliding off the
pan.

Bore a hole in the base between the two spools and pass the wire
through this hole, under the spool in the paraffin, then through a
small hole in the leather and a notch in the block A, and a notch
between the base and the pan. Tie a string around the wire between
the leather and the paraffin, making the knots so they will not
pull through the hole in the leather. This makes the wire smooth,
and by making the string tighter or looser you can regulate the
thickness of the paraffin, says Electrician and Mechanic. Place
the pan on the stove; when the paraffin is melted, pull out the
wire as needed. To keep the pan from sliding place a flatiron or
some other weight on it.

[Illustration: Home-Made Apparatus for Paraffining Wire]



** Uses of Peat [161]

Peat is used in Germany for bedding, fodder, filter, fuel and
packing purposes.



** Scientific Explanation of a Toy [162]

In a recent Issue of Popular Mechanics an article on "The Turning
Card Puzzle" was described and illustrated. Outside of the
scientific side involved herein I describe a much better trick.
About the time when the expression "skidoo" first began to be used
I invented the following trick and called it "Skidoo" and
"Skidee," which created much merriment. Unless the trick is
thoroughly understood, for some it will turn one way, for others
the opposite way, while for others it will not revolve at all. One
person whom I now recall became red in the face by shouting skidoo
and skidee at it, but the thing would not move at all, and he
finally, from vexation, threw the trick into the fire and a new
one had to be made. Very few can make it turn both ways at will,
and therein is the trick.

Take a piece of hardwood 3/8-in. square and about 9 in. long. On
one of the edges cut a series of notches as indicated in Fig 1.
Then slightly taper the end marked B until it is nicely rounded as
shown in Fig. 2. Next make an arm of a two-arm windmill such as
boys make. Make a hole through the center of this one arm. Enlarge
the hole slightly, enough to allow a common pin to hold the arm to
the end B and not interfere with the revolving arm. Two or three
of these arms may have to be made before one is secured that is of
the exact proportions to catch the vibrations right.

[Illustration: How to Cut the Notches]

To operate the trick, grip the stick firmly in one hand, and with
the forward and backward motion of the other allow the first
finger to slide along the top edge, the second finger along the
side and the thumb nail will then vibrate along the notches, thus
making the arm revolve in one direction. To make the arm revolve
in the opposite direction--keep the hand moving all the time, so
the observer will not detect the change which the band
makes--allow the first finger to slide along the top, as in the
other movement, the thumb and second finger changing places: e.
g., in the first movement you scratch the notches with the thumb
nail while the hand is going from the body, and in the second
movement you scratch the notches with the nail of the second
finger when the hand is coming toward the body, thus producing two
different vibrations. In order to make it work perfectly (?) you
must of course say "skidoo" when you begin the first movement, and
then, no matter how fast the little arm is revolving when changed
to the second movement, you must say "skidee" and the arm will
immediately stop and begin revolving in the opposite direction. By
using the magic words the little arm will obey your commands
instantly and your audience will be mystified. If any of your
audience presume to dispute, or think they can do the same, let
them try it. You will no doubt be accused of blowing or drawing in
your breath, and many other things in order to make the arm
operate. At least it is amusing. Try it and see.
--Contributed by Charles Clement Bradley, Toledo, Ohio.

*     *    *    *    *    *    *

The foregoing article describing the "Skidoo-Skidee Trick"
appeared in a recent issue of Popular Mechanics. I have been told
that a similar arrangement is used by a tribe of Indians in the
state of Washington, by the Hindoos in India, and one friend tells
me that they were sold on the streets of our large cities many
years ago.

This toy interested me so much that I have made an investigation
into the causes of its action, and I think the results may be of
interest.

To operate, one end of the notched stick is held firmly in the
left hand, while with the right hand a nail or match stick is
rubbed along the notched edge, at the same time pressing with the
thumb or finger of the moving hand against the oblique face of the
stick. The direction of rotation depends upon which face is
pressed. A square stick with notches on edge is best, but the
section may be circular or even irregular in shape. The
experiments were as follows:

1. A rectangular stick had notches cut on one face. When the
pressure was applied upon a face normal to the first, no rotation
resulted. If the pressure was upon an edge, rotation was obtained.

2. Irregular spacing of the notches did not interfere with the
action. The depth of the notches was also unimportant, although it
should be suited to the size of the nail for best results.

3. The hole in the revolving piece must be larger than the pin; if
there is a close fit no rotation is obtained.

4. The center of gravity of the revolving piece must lie within
the hole. If the hole is not well centered the trick cannot be
performed.

5. If the stick be clamped in a vise no results are obtained; with
this exception: if the stick has enough spring, and the end
clamped is far enough away from the notched portion, the rotation
may be obtained.

The above experiments led me to the conclusion that the operation
of the device is dependent upon a circular motion of the pin, and
this was confirmed by the following experiments. The action is
somewhat similar to swinging the toy known as a locust around with
a slight circular motion of the hand, It is necessary to show here
that a slight circular motion is sufficient to produce the result
and, secondly, that such motion can be produced by the given
movements of the hands.

6. A piece of brass rod was clamped in the chuck of a lathe, and a
depression made in the end slightly eccentric, by means of a
center punch. If the end of the pin is inserted in this
depression,

[Illustration: The Lathe Experiment]

while the hand holding the other end of the stick is kept as
nearly as possible in the axis of the lathe, rotation of the lathe
will produce rotation of the revolving piece. Speeds between 700
and 1,100 r. p. m. gave the best results.

7. A tiny mirror was attached to the end of the pin, and the hand
held in the sunlight so that a spot of sunlight was reflected upon
the wall. The notches were then rubbed in the usual way. The spot
of light upon the wall moved in a way which disclosed two
components of motion, one circular and one due to the irregular
movements of the hand holding the stick. Usually the orbit was too
irregular to show a continuous and closed circular path, but at
times the circular motion became very pronounced. It was observed
and the direction of rotation correctly stated by a man who was
unaware of the source of the motion. The production of the
circular motion can be explained in this way:

When the rubbing nail comes to a notch the release of pressure
sends the stick upward; this upward motion against the oblique
pressure upon the (say) right hand side gives also a lateral
component of motion towards the left. As the nail strikes the
opposite side of the notch the stick is knocked down again, this
motion relieves somewhat the oblique pressure from the right hand
side, and, the reaction from the holding (left) hand moves the
stick to the right slightly, so that it is back in the old
position for the next upward motion. Thus a circular or elliptic
motion is repeated for each notch, and the direction of this
motion is the same whether the nail be rubbed forward or back. For
oblique side pressure from the right (notches assumed upward), the
motion of the stick and hence of the revolving piece will be
counter-clockwise; if the pressure is from the left, it will be
clockwise.

That the motion of the revolving piece is due to a swinging
action, and not to friction of the pin in the hole, is proved by
experiments 3 and 4.
--Contributed by M. G. Lloyd, Ph.D., Washington, D. C.



** Home-Made Lantern [163]

[Illustration: Tin Can Lantern]

The accompanying picture shows a lantern which can be made almost
anywhere for immediate use. All that is needed is an empty tomato
or coffee can, a piece of wire and a candle. Make a hole a little
smaller than the diameter of a candle and about one-third of the
way from the closed end of the can, as shown. A wire is tied
around the can, forming a handle for carrying. This kind of
lantern can be carried against almost any wind and the light will
not be blown out.
--Contributed by G. A. Sloan, Duluth, Minn.



** A Study of Splashes [164]

When a rough, or greasy, or dusty sphere falls into a liquid, the
liquid is

[Illustration: Splashes from a Sphere In Milk and Water]

forced away from the sphere. If the sphere is quite smooth the
liquid rises up around and enclosing it in a sheath says Knowledge
and Scientific News.

Reproduced herewith are a series of photographs showing successive
stages in the entry of a rough sphere into milk and water, and the
resultant "basket splash." The diameter of this sphere was about
3/5 in., and the height of the fall about 6 in. Examination of the
photographs shows that the liquid, instead of flowing over and
wetting the surface of the sphere, is driven violently away, so
far as can be seen from the photographs, the upper portion is, at
first, unwetted by the liquid. The gradual thickening of the
crater wall and the corresponding reduction in the number of its
lobes as the subsidence proceeds is beautifully shown. Thereafter
there rises from the depth of the crater an exquisite jet which in
obedience to the law of segmentation at once splits up in its
upper portion into little drops, while at the same time it gathers
volume from below and rises ultimately as a tall, graceful column
to a height which may be even greater than that from which the
sphere fell.



** How to Make a Stick Pin [164]

A fine stick pin or button can be made from a new one-cent piece.
Carefully file out all the metal around the Indian head and
slightly round the edges. Solder a pin to the back of the head
when it is to be used for a stick pin. If a collar button base is
soldered to the back of the head instead of the pin it can be used
for a button. These can be gold plated by a jeweler and then you
will have a neat pin or button, or a good emblem for the Order of
Redmen.

[Illustration: Stick Pin]



** How to Make a Miniature Electric Locomotive [165]

A miniature electric railway is a thing that attracts the
attention of almost any person. The cost of a toy electric
locomotive is beyond the reach of many boys who could just as well
make such a toy without much expense and be proud to say they
"built it themselves." The electric locomotive described herewith
uses for its power a small battery motor costing about $1. The
first thing to do is to make the wheels and axles. If one has no

[Illustration: The Different Parts for Making the Electric
Locomotive]

lathe, the wheels can be turned at some machine shop. Four wheels
are made from a round bar of metal, as shown in Fig. 1. Each wheel
is 1/4 in. thick and 1 in. in diameter, with a 1/16-in. flange and
a 1/4-in. hole drilled in the center. Each pair of wheels is
fitted on a 1/4-in. axle, about 2-5/8 in. long. One of the axles
should be fitted with a grooved belt wheel, as shown. Make the
frame from three pieces of heavy brass, as shown in Fig. 2.

The first piece, or main part of the frame, is made from brass,
3/4 in. wide and 16 in. long, bent into an oblong shape and the
ends soldered or bolted together. If the ends are to be soldered,
before doing so drill four 1/4-in. holes 1 in. from the ends and
insert the ends of the axles. The other two pieces are 1/2-in.
wide and of the dimensions shown in the sketch. These pieces are
riveted in the middle of the oblong frame, each in its proper
place. The motor is now bolted, bottom side up, to the top of the
piece fastened to the frame lengthwise. A trolley, Fig. 3, is made
from a piece of clock spring, bent as shown, and a small piece of
tin soldered to the top end for a brush connection. A groove is
made in the tin to keep the trolley wire in place.

The trolley wire is fastened to supports made of wood and of the
dimensions given in Fig. 4. The trolley should be well insulated
from the frame. The parts, put together complete, are shown in
Fig. 5. Run a belt from the pulley on the motor to the grooved
wheel on the axle, as shown in Fig. 6, and the locomotive is ready
for running.

In making the connections the travel of the locomotive may be made
more complicated by placing a rheostat and controlling switches in
the line, so that the engine can be started and stopped at will
from a distance and the speed regulated. Automatic switches can be
attached at the ends of the line to break the circuit when the
locomotive passes a certain point.

One connection from the batteries is made to the trolley wire and
the other to a rail. The connection for the motor runs from one
binding post to the trolley and this connection must be well
insulated to avoid a short-circuit. The other binding-post is
connected to the frame.

The cost of making the wheels and purchasing the track will not be
over $1.50. The track can be made from strips of tin put in a saw
cut made in pieces of wood used for ties. This will save buying a
track.
--Contributed by Maurice E. Fuller, San Antonio, Texas.



** Demagnetizing a Watch [166]

A test can be made to know if your watch is magnetized by placing
a small compass on the side of the watch nearest the escapement
wheel if the compass pointer moves with the escapement wheel the
watch is magnetized. A magnetized watch must be placed in a

[Illustration: Watch Demagnetizer]

coil that has an alternating current of electricity flowing
through it to remove the magnetism. A demagnetizer can be made as
shown in the illustration. Two end pieces for the coil are made as
shown in Fig. 1 from 1/4-in. wood. These ends are fastened
together, Fig. 2, with cardboard 3 in. long glued to the inside
edges of the holes cut in them. Wind upon the spool thus formed
about 2 lb. of No. 16 cotton-covered copper wire. As it will be
necessary to place a 16-cp. lamp in series with the coil, both the
coil and lamp can be mounted on a suitable base and connected as
shown in Fig. 3. The current, which must be 110 volt alternating
current, is turned on the lamp and coil and the magnetized watch
slowly drawn through the opening in the center of the coil.
--Contributed by Arthur Liebenberg, Cincinnati, O.



** How to Make a Pocket Skate Sharpener [166]

Secure a square file and break off a piece, Fig 1, the length of a
paper clip, Fig. 2. Draw the temper in the ends of this piece of
file, but do not heat the center. This can be done by wrapping a
wet piece of cloth or asbestos around the middle and holding it in
the jaws of a pair of tongs which will only leave the end
uncovered and projecting from the tongs about 1/2 in. Hold this
projecting end in a flame of a plumber's torch until it is a dull
red. Allow this to cool slowly while in the tongs. When cold treat
the other end in the same way. This will draw the temper in only
the ends which are filed, as shown in Fig. 1, and holes drilled in
them. Also drill a hole in each end of the spring on the paper
clip to match those drilled in the piece of file. Fasten the file
in the clip with small bolts, as shown in Fig. 3. When the file
gets filled with filings it can be removed and cleaned. Place the
runner of the skate in the clip and hold flat on the surface of
the runner. If the piece of file is fitted to the same width as
the skate runner the sides of the paper clip will hold the file
level with the surface of the runner without any trouble. Push the
clip back and forth until the skate is sharpened.

[Illustration: Sharpener for Skates]



** Old-Time Magic [167]



** Trick with a Coin in a Wine Glass [167]

The accompanying sketch shows a. trick of removing a dime from the
bottom of an old fashioned wine glass without touching the coin.
The dime is first placed in the bottom of the glass and then a
silver quarter dropped in on top. The quarter will not go all the
way down. Blow hard into the glass in the position shown and the
dime will fly out and strike the blower on the nose.

[Illustration: Coin Trick]



** Untying-a-Knot Trick [167]

Tie a double knot in a silk handkerchief, as shown in the
accompanying sketch and tighten the last tie a little by slightly
drawing the two upper ends; then continue to tighten much more,
pulling vigorously at the first corner of the handkerchief, and as
this end belongs to the same corner it cannot be pulled much
without loosening the twisted line of the knot to become a
straight line. The other corner forms a slip knot on the end,
which can be drawn out without disturbing the form, or apparent
security of the knot, at the moment when you cover the knot with
the unused part of the handkerchief. When the trick is to be
performed, tie two or three very hard knots that are tightly drawn
and show your audience that they are not easy to untie. The slip
knot as described then must be made in apparently the same way

[Illustration: Knot Trick]

and untied with the thumb while the knot is in the folds of the
handkerchief.



** Gear-Cutting Attachment for Small Lathes [167]

When in need of small gears for experimental or model machines the
amateur usually purchases them, never thinking that he could make
them on his own lathe. A small attachment can be made to fasten in
the tool post of a lathe and the attachment made to take a mandrel
on which to place the blank for cutting a gear. The frame is made
from a 1/2 in. square iron bent as shown in the sketch with the

[Illustration: Gear-Cutting Attachment for Lathes]

projecting end filed to fit the tool post of the lathe. A pair of
centers are fitted, one of which should have a screw thread and
lock nut for adjustment in putting in and removing the mandrel.

All the old clock wheels that can be found should be saved and
used for index wheels. All of these wheels should be fitted to one
end of the mandrel. The blank wheel is put on the outer end of the
mandrel and a clock wheel having the number of teeth desired
placed on the other end. When the mandrel is put in between the
centers a small pawl is fastened with a screw to the frame with
its upper end engaging in a tooth of the clock wheel. One clock
wheel will index more than one number of teeth on a blank wheel.
For instance: if the clock wheel has 18 teeth it can be made to
index 6, 9 or 18 teeth to the blank by moving the number of teeth
each time 3, 2 and 1 respectively. In the sketch, A shows the end
of the cutter and B the side and the shape of the cutting tool.
When the cutter A, which is in a mandrel placed in the centers of
the lathe, has finished a cut for a tooth, the pawl is disengaged
and the mandrel turned to another tooth in the clock wheel.

In order to get the desired height it is sometimes necessary to
block up the lathe head and the final depth of the tooth adjusted
by the two screws in the projecting end of the frame which rests
on the rocker in the tool post. Should too much spring occur when
cutting iron gears the frame can be made rigid by blocking up the
space between it and the lathe bed.

The cutter mandrel is placed in the centers of the lathe, or
should the lathe head be raised, a short mandrel with the cutter
near the end can be placed in a chuck, and adjusted to run true.
The frame holding the mandrel, gear blank and clock wheel is
inserted in the tool post of the lathe and adjusted for depth of
the cutter. The lathe is started and the gear blank fed on the
cutter slowly until the tooth is cut. The pawl is released and the
mandrel turned to the proper number of teeth and the operation
repeated. In this manner gears 3 in. in diameter can be made on a
6-in. swing lathe.
--Contributed by Samuel C. Bunker, Brooklyn, N.Y.



** Wire Terminals for Battery Connections [168]

[Illustration: Cotter Pin Wire Terminal]

Good connections on the end of wires for batteries can be made
from cotter pins, Fig. 1, about 1-1/2 in. long. Each end of the
wire is put through the eye of a cotter pin, twisted around itself
and soldered. The connection and eye are then covered with tape as
shown in Fig. 2. When connecting to batteries, spread the pin and
push the parts under the nut with one part on each side of the
binding-post. When the nuts are tightened the connection will be
better than with the bare wire.
--Contributed by Howard S. Bott.



** Simple Arts and Crafts Leather Work [168]

Very interesting and useful pieces of leather work can be done
with nothing more for equipment than a cup pointed nail set such
as carpenter use, and a nut pick.

The accompanying illustrations show some of the things that can be
made. Beginning at the left and reading to the right they are:
Case for court-plaster, coin purse, lady's card case, eye glass
cleaner or pen wiper (has chamois skin within). Second row: Two
book marks, note book, blotter back, book mark. Third row: Pin
ball (has saddler's felt between the two leather disks), tea
cosey, gentleman's card case or bill book. Fourth row: Needle or
pin case, tea cosey, lady's belt bag, watch fob ready for
fastenings.

Procure a piece of Russian calf modeling leather. (1.) Make on
paper the design wanted. (2.) Moisten the back side of the leather
with sponge or cloth with as much water as it will take yet not
show through on the face side. (3.) Place the leather on some hard
non-absorbent material, such as brass or marble. (4.) Place the
paper design on the leather and, holding it in place with the left
hand, trace the outline, of the object and the decorative design
with the nut pick so as to make a V-shaped groove in the leather.
(5.) Take the paper off and working on the leather directly make
the grooves deeper. (6.) With the cup-pointed nail set stamp the
background promiscuously. This is done by making an effort to hold
the point of the set about 1/4 in. above the surface, at the same
time striking light, rapid blows on the top with a hammer or
mallet.

[Illustration: This Work Is Done with a Nail Set and Nut Pick]

With such objects as coin purses and card cases, a sewing machine
will be needed to fasten the parts together. An ordinary machine
will do. Frequently the parts are fastened by punching holes and
lacing through these with leather thongs or silk cord.

In making symmetrical designs such as are here shown, draw center
lines across the required space, dividing it into as many parts as
desired. Make free-hand one quarter of the design, if four parts
are to be alike, or one-half of the design, if but two parts. Fold
over along these center lines. Put a piece of double-surfaced
carbon paper between the parts and trace over the design already
drawn.



** How to Make a Simple Still [170]

A still to distill water can be made from a test tube, some heavy
rubber hose, and an ordinary bottle. Secure

[Illustration: Distilling Water]

a stopper for the test tube, and bore a hole through the center,
into which fit a small piece of tube. The bottle is also fitted
with a stopper containing a piece of tube, and both bottle and
test tube connected with a rubber tube.

The test tube is partly filled with water and supported or held
over an alcohol lamp. The bottle should stand in a basin of cold
water. When the water in the test tube begins to boil the steam
passes over to the bottle, where it condenses. The basin should be
supplied with cold water as fast as it begins to get warm. The
rubber tube will not stand the heat very long and if the still is
to be used several times, a metal tube should be supplied to
connect the test tube and bottle.



** Homemade Mariner's Compass [170]

Magnetize an ordinary knitting needle, A, and push it through a
cork, B, and place the cork exactly in the middle of the needle.
Thrust a pin, C, through the cork at right angles to the needle
and stick two sharpened matches in the sides of the cork so that
they will project downward as shown. The whole arrangement is
balanced on a thimble with balls of wax stuck on the heads of the
matches. If the needle is not horizontal, pull it through the cork
to one side or the other, or change

[Illustration: Magnetized Needle Revolving on a Pin]

the wax balls. The whole device is placed in a glass berry dish
and covered with a pane of glass.



** Brighten White Paint [170]

Add aluminum bronze to a white or light paint that is to be used
for lettering on a dark ground.



** Quartz Electrodes Used in Receiving Wireless Messages [170]

[Illustration: Details of the Receiving Instrument]

Wireless messages have been received at Washington, D.C., from Key
West, Florida, a distance of 900 miles, through a receiving
instrument in which two pieces of quartz of different composition
were used on the electrodes. In making an instrument of this kind
the quartz can be purchased from a dealer in minerals. One piece
must contain copper pyrites and the other zincites. The electrodes
are made cupping to hold the minerals and each should have a screw
adjustment to press the pieces of quartz in contact with each
other. Connect as shown in the illustration, using a high
resistance receiver.
--Contributed by Edwin L. Powell, Washington, D. C.



** How to Make a Glider [171]
By Carl Bates

A gliding machine is a motorless aeroplane, or flying-machine,
propelled by gravity and designed to carry a passenger through the
air from a high point to a lower point some distance away. Flying
in a glider is simply coasting down hill on the air, and is the
most interesting and exciting sport imaginable. The style of
glider described in this article is known as the "two-surface" or
"double-decked" aeroplane, and is composed of two arched cloth
surfaces placed one above the other.

In building a glider the wood material used should be
straight-grained spruce, free from knots. First prepare from
spruce planks the following strips of wood. Four long beams 3/4
in. thick, 1-1/4 in. wide and 20 ft. long; 12 crosspieces 3/4 in.
thick, 3/4 in. wide and 3 ft. long; 12 uprights 1/2 in. thick,
1-1/2 in. wide and 4 ft long; 41 strips for the bent ribs 3/16 in.
thick, 1/2-in. wide and 4 ft. long; 2 arm sticks 1 in. thick, 2
in. wide and 3 ft. long; the rudder sticks 3/4 in. square and 8 ft
long; several strips 1/2 in. by 3/4 in. for building the vertical
and horizontal rudders. The frames for the two main surfaces
should be constructed first, by bolting the crosspieces to the
long beams at the places shown by the dimensions in Fig. 1. If
20-ft. lumber cannot be procured, use 10-ft. lengths and splice
them, as shown in Fig. 3. All bolts used should be 1/8 in. in
diameter and fitted with washers on both ends. These frames formed
by the crosspieces should be braced by diagonal wires as shown.
All wiring is done with No. 16 piano wire.

The 41 ribs may be nailed to the main frames on the upper side by
using fine flat-headed brads 7/8 in. long. These ribs are spaced 1
ft. apart and extend 1 ft. beyond the rear edges of the main
frames, as shown in Fig. 1. After nailing one end of a rib to the
front long beam, the rib is arched by springing down the loose end
and nailing to the rear beam. The ribs should have a curve as
shown in Fig. 2, the amount of curvature being the same in all the
ribs.

The frames of the main surfaces are now ready to be covered with
cloth. Cambric or bleached muslin should be used for the covering,
which is tacked to the front edge, stretched tightly over the bent
ribs and fastened securely with tacks to the rear ends of the
ribs. The cloth should also be glued to the ribs for safety. In
the center of the lower plane surface there should be an opening 2
ft. wide and 4 ft. long for the body of the operator. Place the
two main surfaces 4 ft. apart and connect with the 12 uprights,
placed in the corner of each crosspiece and beam. The uprights are
fastened by bolting to the crosspieces, as shown in Fig. 2. The
whole structure is made strong and rigid by bracing with diagonal
wires, both laterally and longitudinally.

The vertical rudder is to keep the machine headed into the wind
and is not movable. This rudder is made of cloth stretched over a
light wooden frame, which is nailed to the rudder sticks
connecting to the main frame. The horizontal rudder is also made
of cloth stretched over a light wooden frame, and arranged to
intersect the vertical rudder at its center. This rudder is held
in position and strengthened by diagonal wires and guy wires. The
horizontal rudder is also immovable and its function is to prevent
the machine from diving, and also to keep it steady in its flight.
The rudders are fastened to the glider by the two rudder sticks,
and these sticks are held rigid by diagonal wire and also by guy
wires leading to the sides of the main frames as shown in Fig. 1.
The two arm sticks should be spaced about 13 in. apart and bolted
to the long beams in the center of the opening in the lower plane
where the operator is to take his position.

The glider should be examined to see

[Illustration: Details of the Glider]

that the frame is not warped or twisted. The surfaces must be true
or the machine will be hard to balance when in flight. To make a
glide, take the glider to the top of a hill, get in between the
arm sticks and lift the machine up until the arm sticks are under
the arms as shown run a few steps against the wind and leap from
the ground. You will find that the machine has a surprising amount
of lift, and if the weight of the body is in the right place you
will go shooting down the hillside in free flight. The landing is
made by pushing the weight of the body backwards. This will cause
the glider to tip up in front, slacken speed and settle. The
operator can then land safely and gently on his feet. Of course,
the beginner should learn by taking short jumps, gradually
increasing the distance as he gains skill and experience in
balancing and landing.

The proper position of the body is slightly ahead of the center of
the planes, but this must be found by experience. The machine
should not be used in winds blowing faster than 15 miles an hour.
Glides are always made against the wind, and the balancing is done
by moving the legs. The higher the starting point the farther one
may fly. Great care should be exercised in making landings;
otherwise the operator might suffer a sprained ankle or perhaps a
broken limb. The illustration shows two lines of flight from a
hilltop, the glider travels on the upper line caused by the body
of the operator taking a position a little back of the proper
place, and on the lower line he changes his position from front to
back while flying, which causes the dip in the line.



** Boys Representing the Centaur [173]

This is a diversion in which two boys personate a Centaur, a
creature of Greek mythology, half man and half horse. One of the
players stands erect and the other behind him in a stooping
position with his hands upon the first player's hips, as shown in
Fig. 1. The

[Illustration: Making Up the Centaur]

second player is covered over with a. shawl or table cover which
is pinned around the waist of the first player. A tail made of
strips of cloth or paper is pinned to the rear end of the cover.
The first player should hold a bow and arrow and have a cloak
thrown loosely over his shoulder as shown in Fig. 2. Imitation
hoofs of pasteboard may be made and fastened over the shoes.



** Home-Made Ladle for Melting Babbitt [173]

Secure a large sized old bicycle bell and rivet a heavy wire or
strap iron on one side for a handle. When heated a little, hammer
out the edge on one side for a lip to pour from. This makes a good
ladle for melting small amounts of babbit or lead. --Contributed
by L. M. Olson, Bellingham, Wash



** How to Make a Flash Lamp [174]

Indoor photographs are made much better with the use of a
flashlight than by depending on light from windows. The lighting
can be made from any direction to suit the operator. If lighting
flash powder when not in a regular flash lamp the flash cannot be
depended upon and in some instances is dangerous. To make a simple
and inexpensive flash lamp, first secure from your druggist an
empty salve box about 3 in. in diameter. While at the drug store
get 3 ft. of small rubber tubing; this will cost about 15 cents.
Now visit the tin shop and get a small piece of scrap tin 3 or 4
in. square; a piece of brass or steel wire, about the size of
stove pipe wire, 14 in. long. These with a strip of light asbestos
paper and some small iron wire, about the size of door screen
wire, will complete the material list.

Carefully punch a hole through the salve box on one side near the
bottom with a 10-penny nail. Cut a strip of tin 2 in. long and
about 3/8 in. wide and roll this around a 8-penny nail so as to
form a small tube which will just fit the hole made in the salve
box. Next roll up a strip of tin 1/2 in. wide into a small cup
about 3/8 in. in diameter at one end and 1/4 in. at the other.

Place the tube in the nail hole so that one end comes almost to
the center of the box inside and the other end projects about 1/2
in. outside the box. Cut out a little place for the tube to enter
the cup at the small end and then solder the tube and cup to the
bottom of the box as shown in the illustration. The tube and cup
should be well soldered on the seams to make them airtight. Bend a
ring on one end of the larger piece of wire, making it 2-1/2 in.
in diameter and form the remaining portion of the wire into a
spiral, soldering the end in the bottom of the box near the cup.
Wrap the ring at the top of the spiral piece of wire all the way

[Illustration: Made from a Tin Salve Box ]

around with the strip of asbestos paper, wrapping them together
over and over until the entire ring is covered. Slip the end of
the rubber tube over the tin tube on the side of the box and the
flash lamp is complete.

To make a flash with this lamp fill the little cup in the center
with flash powder and moisten the asbestos ring with alcohol. When
all is ready for the picture the alcohol is lighted and a quick
blow of the breath through the rubber tube will force the flash
powder upward into the flame and cause the flash.

When through with the lamp place the cover over it, pushing the
asbestos ring down inside the box. Wind the rubber tubing around
the box and you have a neat outfit that can be carried in the
pocket.



** Photographing the New Moon [174]

To make a photograph of the moon is quite difficult and no good
picture can be made without an expensive apparatus. At home and
with your own hand camera you can make a good picture of the new
moon by the use of a flash light on a tennis ball, the tennis ball
taking the part of the moon. The ball is suspended in front of a
black cloth screen, the camera focused by holding a burning match
near the ball and the exposure made by burning a

[Illustration: Tennis Ball Photographed]

small quantity of flash powder at one side and a little below the
ball. The light from the flash only striking one side of the ball
gives the effect of the new moon. --Photo by M. M. Hunting,
Dayton, O.



** Old-Time Magic- Part II [175]



** Removing Scissors from a Cord [175]

A piece of strong cord is doubled and fastened to a pair of
scissors with a slip knot, as shown in Fig. 1. After passing the
ends of the cord through the thumb hole of the scissors they are
tied fast to a chair, door knob or any other object that may be of
sufficient size to make the ends secure. The trick is to release
the scissors without cutting the cord.

Take hold of the loop end of the cord in the lower handle and
drawing it first

[Illustration: How the Scissors Are Removed]

through the upper handle and then completely over the blades of
the scissors, as shown in Fig. 2. This is very simple when you
know how, but puzzling when the trick is first seen.



** Coin and Card on the First Finger [175]

This is a simple trick that many can do at the first attempt,
while others will fail time after time. It is a good trick to
spring upon a company casually if you have practiced it
beforehand. A playing card is balanced on the tip of the
forefinger and a penny placed on top immediately over the finger
end, as shown in the sketch. With the right hand forefinger and
thumb strike the edge of the card sharply. If done properly the
card will flyaway, leaving the penny poised on the finger end.

[Illustration: Coin and Card]



** How to Make Sealing Wax Hat Pins [175]

Select a stick of sealing wax of the desired color for the
foundation of the hat pin. Hold the end of the stick over a flame
until the wax is soft enough to drop; then put it on the hat-pin
head. When sufficient wax has adhered to the pin, hold the lump
over the flame, revolving the pin at the same time so the wax will
not drop and the head will form a round ball. The head can be made
in any shape desired while warm. When the desired shape has been
obtained, cool thoroughly in cold water and dry carefully.

Stripes and designs may be put on the foundation by applying drops
of other brilliant colored wax, and by careful manipulation the
wax when warm can be made to flow around the pin head and form
pretty stripes and designs. If a certain color is to be more
prominent, the wax to make this color must be applied last and the
pin put through the flame again. Cool in water and dry, as before,
and pass once more through the flame to obtain the luster.



** Old-Time Magic-Part III [176]



** Disappearing Coin [176]

While this is purely a sleight-of-hand trick, it will take very
little practice to cause the coin to disappear instantly. Take a
quarter of a dollar between the thumb and finger, as shown, and by
a rapid twist of the fingers whirl the coin and at the same time
close the hand, and the coin will disappear up your coat sleeve.
On opening the hand the coin will not be seen. Take three quarters
and hold one in the palm of the left hand, place the other two,
one between the thumb and finger of each hand, then give the coin
in the right hand a whirl, as described, closing both hands
quickly. The coin in the right hand will disappear up your sleeve,
and the left hand on being unclosed will contain two quarters,
while the one in the right shall have disappeared.

[Illustration: Disappearing Coin]



** Sticking a Coin Against the Wall [176]

Cut a small notch in a coin--ten cent piece or quarter will do--so
a small point will project. When this is pressed firmly against a
wood casing or partition the coin will stick tightly.



** A Chinese Outdoor Game [176]

The accompanying illustration shows the "grand whirl," or the
Chinese students' favorite game. This game is played by five
persons, four of them turning around the fifth or central figure

[Illustration: Chinese Doing the Grand Whirl]

with their arms locked about each other and the two outside
persons swinging in midair with their bodies almost horizontal.



** Home-Made Photograph of a Lightning Flash [176]

How many times has each amateur photographer tried to photograph
the lightning's flash? Some good pictures have been obtained by a
ceaseless effort on the part of the operator. Here is a method by
which you can make a picture of a streak of lightning on a clear
night in your own house. Paste two strips of black paper on a
piece of glass that is 10 in. square so as to leave a clear space
through the center 2-in. or more in width. Smoke this uncovered
space over a candle's flame until the soot is thick enough to
prevent light passing through. Take a sharp lead pencil and
outline a flash of lightning upon the smoked surface, using a fine
needle to make the smaller lines, and then set the glass up
against the back of two boxes which are set to have a space
between them of 4 or 5 in.

A lighted candle is held behind the glass so the light will shine
through for focusing the camera. After darkening the room set your
camera ready for the exposure and burn a small quantity of flash
light powder in the same place in which the candle was held. This
will make an impression upon the plate of the flash drawn on the
smoked glass.

[Illustration: Lightning Flash]



** How to Make a Static Machine [177]

Static electricity is produced by revolving glass plates upon
which a number of sectors are cemented; these sectors, passing
through neutralizing brushes, distribute electric charges

[Illustration: Details of a Homemade Static Machine]

to collecting combs attached to discharging rods. The glass
selected for the plates must be clear white glass, free from
wrinkles, and of a uniform thickness. Two plates are necessary to
make this machine, and the glass should be of sufficient size to
cut a circular plate 16-in. in diameter. A hole must be made
exactly in the center of each plate, and this should be done
before cutting the circle. One of the best ways to make the hole
is to drill the glass with a very hard-tempered drill, the cutting
edge of which should be kept moistened with 2 parts turpentine and
1 part sweet oil while drilling. The hole is to be made 3/4 in. in
diameter. The circle is then marked on each plate and cut with a
glass cutter. The plates are trued up, after they are mounted, by
holding a piece of emery wheel to the edges while they are
turning. Water should be applied to the edges while doing the
work.

The sectors are cut from tinfoil, 1-1/2 in. wide at one end, 3/4
in. at the other, and 4 in. long. A thin coat of shellac varnish
is applied to both sides of the plates, and 16 sectors put on one
side of each plate, as shown in Fig. 1. The divisions can be
marked on the opposite side of the plate and a circle drawn as a
guide to place the sectors at proper intervals.

The sectors should lie flat on the glass with all parts smoothed
out so that they will not be torn from their places as the plates
revolve. The shellac should be tacky when the pieces of tinfoil
are put in place.

The collectors are made, as shown in Fig. 2, from about 1/4-in.
copper wire with two brass balls soldered to the ends. The fork
part is 6 in. long and the shank 4 in. Holes are drilled on the
inside of the forks, and pins inserted and soldered. These pins,
or teeth, should be long enough to be very close to the sectors
and yet not scratch them when the plates are turning.

The frame of the machine is made from any kind of finished wood
with dimensions shown in Fig. 3, the side pieces being 24 in. long
and the standards 3 in. wide. The two pieces, C C, Fig. 3, are
made from solid, close grained wood turned in the shape shown,
with the face that rests against the plate 4 in. in diameter, and
the outer end 1-1/2 in. in diameter, the smaller end being turned
with a groove for a round belt. Before turning the pieces a hole
is bored through each piece for the center, and this hole must be
of such a size as to take a brass tube that has an internal
diameter of 3/4 in. The turned pieces are glued to the glass
plates over the center holes and on the same side on which the
sectors are fastened. Several hours' time will be required for the
glue to set. A fiber washer is then put between the plates and a
brass tube axle placed through the hole. The plates, turned wood
pieces, and brass axle turn on a stationary axle, D.

The drive wheels, EE, are made from 7/8-in. material 7 in. in
diameter, and are fastened on a round axle cut from a broom
handle. This wood axle is centrally bored to admit a metal rod
tightly, and extends through the standards with a crank attached
to one end.

Two solid glass rods, GG, Fig. 4, 1 in. in diameter and 15 in.
long, are fitted in holes bored into the end pieces of the frame.
Two pieces of 1-in. brass tubing and the discharging rods, RR, are
soldered into two hollow brass balls 2 or 2-1/2 in. in diameter.
The shanks of the collectors are fitted in these brass balls with
the ends extending, to which insulating handles are attached.
Brass balls are soldered to the upper ends of the discharging
rods, one having a 2-in. ball and the other one 3/4 in. in
diameter.

Caps made from brass are fitted tightly on the ends of the
stationary shaft, D, and drilled through their diameter to admit
heavy copper rods, KK, which are bent as shown. Tinsel or fine
wire such as contained in flexible electric wire are soldered to
the ends of these rods, and the brushes thus made must be adjusted
so they will just touch the plates. The caps are fitted with
screws for adjusting the brushes. These rods and brushes are
called the neutralizers. A little experimenting will enable one to
properly locate the position of the neutralizers for best results.
--Contributed by C. Lloyd Enos, Colorado City, Colo.



** A Concrete Swimming Pool [178]

[Illustration: Home-Made Swimming Pool]

Several boys from a neighborhood in the suburbs of a large city
concluded to make for themselves a swimming tank of concrete. The
money was raised by various means to purchase the cement, and the
work was done by themselves. The ground was selected in a secluded
spot in a neighbor's back yard and a hole dug to a depth of 4 ft.,
12 ft. wide and 22 ft. long. The concrete was made by mixing 1
part cement, 4 parts sand and 10 parts gravel together and the
bulk moistened with water. The bottom was made the same as laying
a sidewalk, and forms were only used for the inside of the
surrounding wall. The tank may be hidden with shrubbery or vines
planted to grow over a poultry wire fence.



** Old-Time Magic-Part IV [179]

Cutting a Thread Inside of a Glass Bottle [179]

This is a trick which can only be performed when the sun shines,
but it

[Illustration: The Glass Directs the Sun's Rays]

is a good one. Procure a clear glass bottle and stick a pin in the
lower end of the cork. Attach a thread to the pin and tie a small
weight to the end of the thread so it will hang inside the bottle
when the cork is in place. Inform your audience that you will
sever the thread and cause the weight to drop without removing the
cork.

All that is required to perform the feat is to hold a magnifying
glass so as to direct the sun's rays on the thread. The thread
will quickly burn and the weight fall.



** Removing a Key from a Double String [179]

Tie the ends of a 5-ft. string together, making a double line on
which a key is placed and the string held as shown by the dotted
lines in the sketch. Turn the palms of the hands toward you and
reach over with the little finger of the right hand and take hold
of the inside line near the left-hand thumb.

[Illustration: "The Key Will Drop from the String"]

Reverse the operation and take hold of the inside line near
right-hand thumb with the little finger of the left hand. You will
then have the string as it appears in the sketch. Quickly let
loose of the string with a little finger on one hand and a thumb
on the other and pull the string taut. The key will drop from the
string.



** How to Bore a Square Hole [179]

You would not consider it possible to bore a square hole in a
piece of cardboard, yet such a thing can be done. Take a cardboard
or a thin piece of wood, fold and place it between two pieces of
board with the fold up; the boards are then put in a vise as
shown. Start the bit with the screw point in the fold, using a
1-in. bit, and bore a

[Illustration: Boring a Square Hole]

hole 1/2 in. deep. When the cardboard is taken from the vise it
will appear as shown at B and when unfolded, as at A.



** HOW TO MAKE COPPER TRAYS [180]

Copper trays such as are shown in the accompanying illustration
are very useful as well as ornamental about the house. They can be
used to keep pins and needles, pens and pencils, or cigar ashes,
etc. They are easily made, require no equipment in the way of
tools except what are usually found about the house, unless it
would be the metal shears, and when the decorations are well
designed and the metal nicely colored, they make attractive little
pieces to have about.

The first thing to do in preparation for making them is to prepare
the design. Simple designs work out better than fussy ones and are
more likely to be within the ability of the amateur. Having
determined the size of the tray, draw on paper an oblong to
represent it. Inside this oblong, draw another one to represent
the lines along which the metal is to be bent up to form the
sides. Inside this there should be drawn still another oblong to
represent the margin up to which the background is to be worked.
The trays shown are 5-3/4 by 6-3/4 in., the small ash tray 4 by 4
in., the long pen and pencil tray 4-3/4 by 9-1/2 in. The second
oblong was 3/4 in. inside the first on all, and the third one 1/4
in. inside the second on all.

If the decoration is to have two parts alike--symmetrical--divide
the space with a line down the middle. Draw one-half the design
free hand, then fold along this line and trace the second half
from this one. If the lines have been drawn with soft pencil,
rubbing the back of the paper with a knife handle will force
enough of the lead to the second side so that the outline can be
determined. Four-part symmetry will require two lines and two
foldings, etc.

For the metal working there will be needed a pair of tin shears,
two spikes, file, flat and round-nosed pliers, screw-driver and
sheet copper of No. 23 gauge. Proceed as follows: 1. Cut off a
piece of copper so that it shall have 1/2 in. extra metal on each
of the four sides. 2. With a piece of carbon paper trace upon the
copper lines that

[Illustration: Articles Made from Copper]

shall represent the margin of the tray proper and the lines along
which the upturned sides of the tray are to be bent; also trace
the decorative design. 3. With a nail make a series of holes in
the extra margin, about 3/4-in. apart and large enough to take in
a 3/4-in. slim screw. 4. Fasten the metal to a thick board by
inserting screws in these holes. 5. With a 20-penny wire nail that
has the sharpness of its point filed off, stamp the background
promiscuously. By holding the nail about 1/4 in. above the work
and striking it with the hammer, at the same time striving to keep
it at 1/4 in. above the metal, very rapid progress can be made.
This stamping lowers the background and at the same time raises
the design. 6. Chase or stamp along the border of the design and
background, using a nail filed to chisel edge. This is to make a
clean, sharp division between background and design. 7. When the
stamping is completed, remove the screws and the metal from the
board and cut off the extra margin with the metal shears. File the
edges until they are smooth to the touch. 8. With the flat pliers
"raise" one side of the tray, then the other side. 9. Raise the
ends, adjusting the corners as shown in the illustration. Use the
round-nosed pliers for this purpose.

Copper is frequently treated chemically to give it color. Very
pretty effects may be obtained by covering the tray with
turpentine, then moving it about over a flame such as a bunsen
burner until the turpentine burns off. The copper will "take on"
almost all the colors of a rainbow, and the effect will be most
pleasing.



** Photograph of a Clown Face [181]

At first glance the accompanying photograph will appear as if the
person photographed is wearing a false face or has his face
painted like a clown. On close observation you will notice that
the face is made on the bald head of the person sitting behind the
table. The eyes, nose and mouth are cut from black paper and
pasted on the bald spot. The subject's face is horizontal and
resting upon his hands.

[Illustration: A Bald Head Photographed]



** Finger Mathematics [181]
By Charles C. Bradley

All machinists use mathematics. Ask a machinist what would be the
product of 9 times 8 and his ready reply would be 72, but change
the figures a little and say 49 times 48 and the chances are that
instead of replying at once he will have to figure it out with a
pencil. By using the following method it is just as easy to tell
at a glance what 99 times 99 are as 9 times 9. You will be able to
multiply far beyond your most sanguine expectations.

In the first numbering, begin by holding your hands with the palms
toward the body and make imaginary numbers on the thumbs and
fingers as follows: Thumbs, 6; first fingers, 7; second fingers,
8; third fingers, 9, and fourth fingers, 10. Suppose you desire to
multiply 8 by 9, put the eighth finger on one hand against the
ninth finger of the other hand as shown.

[Illustration: "8 Times 9"]

The two joined fingers and all the fingers above them (calling the
thumbs fingers) are called the upper fingers and each has a value
of ten, which tens are added. All the fingers below the joined
fingers are termed the lower fingers, and each of the lower
fingers represents a unit value of one. The sum of the units on
one hand should be multiplied by the sum of the units on the other
hand. The total tens added to this last named sum will give the
product desired. Thus: Referring to above picture or to your hands
we find three tens on the left hand and four tens on the right,
which would be 70. We also find two units on the left hand and one
on the right. Two times one are two, and 70 plus 2 equals 72, or
the product of 8 times 9.

Supposing 6 times 6 were the figures. Put your thumbs together;
there are no fingers above, so the two thumbs represent two tens
or 20; below the thumbs are four units on each hand, which would
be 16, and 20 plus 16 equals 36, or the product of 6 times 6.

[Illustration: "6 Times 6"   "10 Times 7"]

Supposing 10 times 7 is desired. Put the little finger of the left
hand against the first finger of the right hand. At a glance you
see seven tens or 70. On the right hand you have three units and
on the left nothing. Three times nothing gives you nothing and 70
plus nothing is 70.

In the second numbering, or numbers above 10, renumber your
fingers; thumbs, 11; first fingers, 12, etc. Let us multiply 12 by
12.

Put together the tips of the fingers labeled 12. At a glance you
see four tens or 40. At this point we leave the method explained
in Case 1 and ignore the units (lower fingers) altogether. We go
back to the upper fingers again

[Illustration: "12 Times 12"]

and multiply the number of upper fingers used on the one hand by
the number of upper fingers used on the other hand, viz., 2 times
2 equals 4. Adding 4 to 40 gives us 44. We now add 100 (because
anything over 10 times 10 would make over 100) and we have 144,
the product of 12 times 12.

The addition of 100 is arbitrary, but being simple it saves time
and trouble. Still, if we wish, we might regard the four upper
fingers in the above example as four twenties, or 80, and the six
lower fingers as six tens, or 60; then returning to the upper
fingers and multiplying the two on the right hand by the two on
the left we would have 4; hence 80 plus 60 plus 4 equals 144;
therefore the rule of adding the lump sum is much the quicker and
easier method.

Above 10 times 10 the lump sum to add is 100; above 15 times 15 it
is 200; above 20 times 20, 400; 25 times 25, 600, etc., etc., as
high as you want to go.

In the third numbering to multiply above 15 renumber your fingers,
beginning the thumbs with 16, first finger 17, and so on. Oppose
the proper finger tips as before, the upper fingers representing a
value of 20. Proceed as in the first numbering and add 200. Take
For example 18 times 18.

At a glance we see six twenties plus 2 units on left hand times 2
units on right hand plus 200 equals 324.

In the fourth numbering the fingers are marked, thumbs, 21, first
fingers 22, etc., the value of the upper fingers being 20. Proceed
as in the second lumbering, adding 400 instead of 100.

[Illustration: "18 Times 18"]

Above 25 times 25 the upper fingers represent a value of 30 each
and after proceeding as in the third numbering you add 600 instead
of 200.

This system can be carried as high as you want to go, but you must
remember that for figures ending in 1, 2, 3, 4 and 5 proceed as in
the second numbering. For figures ending in 6, 7, 8, 9 and 10 the
third numbering applies.

Determine the value of the upper fingers whether they represent
tens, twenties, thirties, forties, or what. For example, any two
figures between 45 and 55, the value of the upper fingers would be
50, which is the half-way point between the two fives. In 82 times
84 the value of the upper fingers would be 80 (the half-way point
between the two fives, 75 and 85, being 80). And the lump sum to
add.

Just three things to remember:

Which numbering is to follow, whether the one described in second
or third numbering; the value which the upper fingers have; and,
lastly, the lump sum to add, and you will be able to multiply
faster and more accurately than you ever dreamed of before.



** Optical Illusions [183]

If a person observes fixedly for some time two balls hanging on
the end of cords which are in rapid revolution, not rotation,
about a vertical axis, the direction of revolution will seem to
reverse. In some experiments two incandescent "pills" of platinum
sponge, such as an used for lighting gas-burners, were hung in
tiny aluminum bells from a mica vane wheel which was turned
constantly and rapidly in one direction by hot air from a gas
flame to keep the platinum in a glow. The inversion and reversion
did not take place, as one might suppose, at the will of the
observer, but was compulsory and followed regular rules. If the
observer watches the rotating objects from the side, or from above
or from below, the inversion takes place against his will; the
condition being that the image on the retina shall be eccentric.
It takes place also, however, with a change in the convergence of
the optical axes, whether they are parallel to each other or more
convergent. Also when the image on the retina is made less
distinct by the use of a convex or concave lens, the revolution
seems to reverse; further, in the case of a nearsighted person,
when he removes his spectacles,

[Illustration: Illusions Shown by Revolving Platinum Sponge
"Pills" and Hat Pins]

inversion results every time that the image on the retina is not
sharp. But even a change in the degree of indistinctness causes
inversion.

The cause of this optical illusion is the same where the wings of
windmills are observed in the twilight as a silhouette. It is then
not a question of which is the front or the back of the wheel, but
whether one of the wings or the other comes towards the observer.
The experiment is made more simple by taking a hat pin with a
conspicuous head, holding it firmly in a horizontal position, and
putting a cork on the point. Looking at it in semi-darkness, one
seems to see sometimes the head of the pin, sometimes the point
towards him, when he knows which direction is right. The inversion
will be continued as soon as one observes fixedly a point at the
side. Here it is a question of the perception of depth or
distance; and this is the same in the case of the rotating balls;
the direction of seeming revolution depends on which one of them
one considers to be the front one and which the rear one.

From the foregoing the following conclusion may be reached: When,
in the case of a perception remitting two appearances, one fixedly
observes one of these and then permits or causes change in the
sharpness of the image on the retina, the other appearance asserts
itself.



** Steam Engine Made from Gas Pipe and Fittings [184]

Almost all the material used in the construction' of the parts for
the small steam engine illustrated herewith was made from gas pipe
and fittings. The cylinder consists of a 3-in. tee, the third
opening being threaded and filled with a cast-iron plug turned to
such a depth that when the interior was bored out on a lathe the
bottom of the plug bored to the same radius as the other part of
the tee. The outside end of the plug extended about 1/4-in. and
the surface was made smooth for the valve seat. A flat slide valve
was used.

The ports were not easy to make, as

[Illustration: The Engine Is About 20 Inches High]

they had to be drilled and chipped out. The steam chest is round,
as it had to be made to fit the round tee connection. The
crosshead runs in guides made from a piece of gas pipe with the
sides cut out and threads cut on both ends. One end is screwed
into a rim turned on the cylinder head and the other is fitted
into an oblong plate. Both ends of this plate were drilled and
tapped to receive 1-1/2-in. pipe.

The main frame consists of one 1-1/2in. pipe 10 in. long and one
made up from two pieces of pipe and a cross to make the whole
length 10 in. These pipes were then screwed into pipe flanges that
served as a base. The open part of the cross was babbitted to
receive the main shaft. The end of the shaft has a pillow block to
take a part of the strain from the main bearing. The eccentric is
constructed of washers. While this engine does not give much
power, it is easily built, inexpensive, and anyone with a little
mechanical ability can make one by closely following out the
construction as shown in the illustration.
--Contributed by W. H. Kutscher, Springfield, Ill.



** How to Make a Copper Bowl [185]

To make a copper bowl, such as is shown in the illustration,
secure a piece of No. 21 gauge sheet copper of a size sufficient
to make a circular disk 6-1/2 in. in diameter.

Cut the copper to the circular form and size just mentioned, and
file the edge so that it will be smooth and free from sharp
places. With a pencil compass put on a series of concentric rings
about 1/2 in. apart. These are to aid the eye in beating the bowl
to form.

The tools are simple and can be made easily. First make a
round-nosed mallet of some hard wood, which should have a diameter
of about 1-1/4 in, across the head. If nothing better is at hand,
saw off a section of a broom handle, round one end and insert a
handle into a hole bored in its middle. Next take a block of wood,
about 3 by 3 by 6 in., and make in one end a hollow, about 2 in.
across and 1/2 in. deep. Fasten the block solidly, as in a vise,
and while holding the copper on the hollowed end of the block,
beat with the mallet along the concentric rings.

Begin at the center and work along the rings--giving the copper a
circular movement as the beating proceeds--out toward the rim.
Continue the circular movement and work from the rim back toward
the center. This operation is to be continued until the bowl has
the shape desired, when the bottom is flattened by placing the
bowl, bottom side up, on a flat surface and beating the raised
part flat. Beating copper tends to harden it and, if continued too
long without proper treatment, will cause the metal to break. To
overcome this hardness, heat the copper over a bed of coals or a
Bunsen burner to a good heat. This process is called annealing, as
it softens the metal.

The appearance of a bowl is greatly enhanced by the addition of a
border. In the illustration the border design shown was laid out
in pencil, a small hole was drilled with a band drill in each
space and a small-bladed metal saw inserted and the part sawed
out.

To produce color effects on copper, cover the copper with
turpentine and

[Illustration: Shaping the Bowl and Sawing the Lace]

hold over a Bunsen burner until all parts are well heated.



** Cleaning Furniture [185]

After cleaning furniture, the greasy appearance may be removed by
adding some good, sharp vinegar to the furniture polish. Vinegar,
which is nothing else than diluted acetic acid, is one of the best
cleansers of dirty furniture.



** Melting Lead in Tissue Paper [185]

Take a buckshot, wrap it tightly in one thickness of tissue paper,
and, holding the ends of the paper in the fingers of each hand,
place the part that holds the shot over the flame of a match just
far enough away from the flame not to burn the paper. In a few
seconds unfold the paper and you will find that the shot has
melted without even scorching the paper.
--Contributed by W. O. Hay, Camden, S. C.



** The Principles of the Stereograph [185]

Each of our eyes sees a different picture of any object; the one
sees a trifle more to the right-hand side, the other to the left,
especially when the object is near to the observer. The
stereoscope is the instrument which effects this result by
bringing the two pictures together in the senses. The stereograph